I would go for an animal associated with trickery and cunning, simply because that is, in a sense, the very nature of chaos.
Wikipedia lists some tricksters in lore, mainly non animals, but a few real animals associated with trickery too. There is also the following passage on the wiki-page
Hynes and Doty, in Mythical Trickster Figures (1997) state that every trickster has several of the following six traits:
- fundamentally ambiguous and anomalous
- deceiver and trick-player
- messenger and imitator of the gods
- sacred and lewd bricoleur
These aspects are often highly associated with chaos and entropy.
So, which animal to choose, then?
Fox! A fox is cute and in most cultures associated with trickery and cunning (I guess everyone knows the saying "as cunning as a fox"). It would be a great image of such goddess.
There are ample of famous trickster foxes:
- Kitsune, the Japanese trickster fox.
- Reynard, famous in several European countries.
- Kuma Lisa from Bulgaria and Russia.
If you don't want a fox, then there are some other animals also associated with trickery:
- Coyote, "the native American version of the fox".
- Anansi, an African spider.
- Puss in boots, even cats can be cunning.
- Raven, while not really associated with trickery, ravens are often associated with omens, knowledge and death, which fits to the chaos part.