3D Printing of food is right around the corner. As an additive process, your astronauts would plug in what they want to eat, and your printer will create it out of layering and fusing granules together in order to prepare your food for you.
The tricky part is that most likely by 2050 technology, the food produced will be very dry, requiring a hydration process. Still, the space requirement for this much food + water for hydration will be dramatically less than today. For example, we know astronauts don't eat bread, because it takes up too much room (and crumbles after a while). Now they can make and eat bread, or let them eat cake.
An astronaut is provided three meals a day. I am speculating that an average "meal" is only 50% efficient in size; that is to say, it's 50% air and water, just by looking at MREs, or imagining breads, pastas, and sauces. Others will be shipped as-is, such as condiments.
Therefore a meal that would be transported via (even vacuum sealed) box can be 50% smaller as granules for printing. A tight meal box measuring 150cm3 can now be 75cm3.
- 75cm3 x 3 meals x 40pax x 5475 days = ~50 cubic meters of storage.
- Water requirement (additional 25%?) = ~3 cubic meters of water (for food hydration only).
- Contingency and Miscellany (additional 20%?) = ~2 cubic meters of space.
Next your astronauts need water, juices, and please let them have at least some alcohol if they're going to be stuck together for 15 years.
If we follow the 2l of hydration per day, this translates to 2,000cm3 per day.
- 2,000cm3 x 40pax x 5475days = 438 cubic meters of space.
- Contingency (20%) = 88 cubic meters of space.
All of the contingency should include delivery space, space for your astronauts to collect it, your printer (and backup printers!), and any spillage or spoilage.
Total = 580 cubic meters of space. Your walk-in storage hall could be 2m high, 2m wide, and 145m long. You can store the champagne and glasses "overhead" or "below the walkway" presuming you have gravity.
But, wait, there's more.
Consider a percentage reduction by using the materials in poop (sorry) and recycled urine (sorry), to reduce the space requirements for feeding your 40.
I ran a restaurant for two years, and a days' worth of food for 40 people could easily be squished into 9000 cubic centimeters, so my numbers might even be too high. Feel free to replace any of the assumptions and percentages to design your space craft.
I am keen to understand why on Earth you want to prioritize Pluto in our space program in the next 35 years.