How do I color a pet galactic?

That's answered in the Subeta F.A.Q.'s Pet section besides many other things. C:

Vic - On the 6th and 7th of each month you can dig for gems in the Coda Caves. Illatho, I think his name is? Anyways, he can bless your pet if you give him gems. Then, tadaaa. Galactic pet.