It's not possible to get colored cats on Petz Clan.
Petz Clan is a website and community focused on the classic "Petz" games, specifically Petz 5. The games themselves don't have the feature of having colored cats. The cats in the game are always the classic grey or brown color, and you cannot change them.
You may be thinking of other "Petz" games or even other virtual pet games that allow for customization, but those are separate from Petz Clan and Petz 5.
If you're interested in virtual pets with more color options, you might want to look into games like:
* Nintendogs
* My Talking Tom
* Pou
* Tamagotchi
I hope this explanation is helpful!