I'm not sure what the answer is but I know that since it is recessive she'd need to have them on both her X chromosomes for her to be color blind (meaning she'd have to inherit the gene from both her parents). Because males have one X (and one Y) they would only need one x-linked recessive gene to be effected with color blindness.
Because of this, color blindness is sex-linked and happens much more in males than females.
