Intelligence is not a singular trait
There are many facets to intelligence. Let's start with some animal examples:
Everybody loves dogs and dogs love everybody. They have incredible social skills and are amazingly adapted to humans. They are the only domesticated animal that runs towards their "human" when frightened and not away. They can read human facial expression naturally. Even most apes have to learn that pointing towards something is not you just randomly raising your arms, but dogs instinctively look where you are pointing (if they trust you) as they understand the gesture.
When it comes to technical/mechanical understanding dogs are incredibly bad. Dogs are barely capable of solving mechanical puzzles to get their treats. They can follow commands to solve it, but they lack the capabilities of solving it on their own.
Dogs are very cooperative. They are very social amongst one another and with humans and can cooperate to achieve a common goal - like hunting. This is the main reason we bred dogs from wolves, originally.
Birds are the exact opposite of dogs regarding the two aspects I highlighted. Crows, for example, can solve mechanical puzzles of several steps to secure their prized treats, but they are absolutely incapable of cooperation. When two birds are sitting in front of a see-through box with treats and a lever they can pull connected to the box, they will quickly find out they can lift the box to reach the treats, but each bird realizes it can not reach the treats while it pulls the lever. So they stop. They could cooperate, one pulls the lever, the other one pulls out the treats, but they will not. Each bird is just thinking of "how can I get the treat?". Cooperation is not ingrained in their psychology.
What we usually refer to as intelligence with humans is mathematical and geometrical understanding. That is what IQ tests are going for in most cases, too.
"Here is a sketch of body X. Draw it rotated 90° to the right." Questions like this are aiming for a persons spatial understanding.
IQ tests are just a rough estimation of a person's skills. They are everything but a precise measurement of intelligence. Intelligence is an abstract concept with many facets that can not be expressed in a singular number. Simply do a second IQ test right after your first and your score will be higher. Just because you know what to expect of the questions you will be quicker and more secure in your decisions. You will not have been getting more intelligent by doing a single IQ test.
Now to the main question.
Could intelligence be bred?
Yes, basically any trait could be artificially selected for. It is more likely for two people with a very healthy and fit body to have children that are more prone to having healthy and fit body. (Same goes for unhealthy, btw.) If you have two people who are strong exhibitors of any trait it is likely that their offspring will be carrying that trait, too.
Intelligence is not a singular trait. There are a many influencing factors, genetically speaking. People with genetic defects like Down-Syndrome can still be perfectly functional humans, but it is significantly less likely for them to be above average in most things they do.
Other factors like high testosterone, estrogen and other hormone levels influence a person's tendencies and traits, too. Every hormone differently and there are always strong exceptions. Biochemistry is the most difficult thing to model precisely.
Does it suffice to just start a colony of intelligent people?
Not necessarily, no. Just because somebody is smart, does not mean they are a good parent. While many traits like physical prowess thrive on exercise, so does intelligence. It is extremely unlikely to grow up to be intelligent, when you have never had any nurturing of this skill. The human brain and body build what they need. When a child's mind is never given any intellectual input, why would it develop a skill to interpret such input?
The intelligent parents' DNA just makes it more likely that the child is going to be good at building up intelligence. If it is never given an opportunity to build it up it will not use that potential.
What you need
...is a program that selects compatible intelligent people and makes sure that they are raised well, including a healthy home environment and parental attention. Early education is important. Focus all of the education and attention on rewarding intellectual skill. This means lots of challenging games from a young age one in which the children can hone their skills. If you want them having a healthy psyche it should always be focusing on rewarding progress instead of demanding progress, the latter works to but comes with side effects I'll talk about below.
An important side note
While you could also create socially incapable, semi-autistic people with a very high IQ with less effort, by ignoring the "healthy" part I mentioned, I would personally advise against it as the people might have advanced skill sets, but their lack of social skills would make it more difficult for these skills to be applied in a productive context.
Besides that, it would also be child abuse. Not too fond of that.