(I'm just going say you can choose anything for every category.)

Main fur color:

Generate a number from 1-8

1- White fur

2- Black fur

3- Red fur

4- Tan fur

5- Light brown fur

6- Dark brown fur

7- Gray fur

8- Calico

Second fur color: (optional)

 Same colors as part one of this, for example 1 is still white and 5 is still light brown, but if you get the same number it's just a lighter or darker shade of that color. And if you get calico just generate again.

Eye color:

Generate a number from 1-8

1- Green 

2- Blue 

3- Amber

4- Red

5- Yellow

6- Gray

7- different colored eyes

8- Multicolored eyes.

Size/Build:

Generate a number from 1-9

1- small and skinny

2- small and average 

3- small and bulky

4- average and skinny

5- average

6- average and bulky

7- bug and skinny

8- big and average 

9- big and bulky

OwlHeart is from ShadowClan and has light brown fur with reddish paws and ears. He has green eyes and is a small cat with an average build.