Calico cats are a beautiful example of sex-linked genetic traits at work. Calico cats are almost always females. Cats have a sex chromosome similar to humans where females have an XX and male have an XY. The pigmentation on calico fur is due to the process of Lyonization. This means that the traits on one X chromosome is activated and one is inactive. This type of allele can only occur when there are two X chromosomes which is why it is unlikely to find a male calico. Although, not impossible.
These color markings on cats could aid in the survival of the cat in the wild. The image above the cat's color markings help the cat camouflage with the tree in order to protect itself from predators or make themselves hard to spot when stalking prey.