To be color blind you need 2 color blind allele. So color blind allele are recessive. In females, color blinds only occur if both of the alleles are recessive.
Cousins are of course biological cousin.
Genetic similarity defined as the partial derivative of expected value of having a color blind allele of a cousin as a function of the percentage of you having color blind allele is 1/8.
I think I should add that color blind alleles are extremely rare. It's actually 5% but you can presume it's .0000001%. However, you, a female, is color blind. What's the chance that your cousin is color blind?