Can you use a COLOR SPECIES elixir, then change the species of your pet with another elixir, but KEEP the same color?

Nope. You'd have to use the species color that you want, or you could use a species elixir and then buy the potion.

K, thanks :)

Miracle Potion II changes your pets species without changing its current color. This also includes Experiment pets. It's the only way to keep a pets color/ change the specie.