Nothing to stop you doing green, blue or other colours. What shade of blue. anyway the more the merrier. Mine will be at the Guild and you are making for ztuf. Plus the habitats are likely to be very different. My comment was not meant to put you off. Mine are a while off too with all the other things I have to do.
Another thing you might like to do is choose an ingame or user made animal you like and make one that has the same exhibit requirements so they can be used in a combined exhibit.
Ohhhh, now there is an idea. Make a flamingo (or a couple of colours) that would go in the ingame tapir exhibit happily.
I still haven't been able to create my own colors, so I'm kind of stuck in a rut right now.