I looked up the McMurray "Red Stars". They are kind of large but are supposedly based on commercial layers.
Leg color is controlled by genetics. Some breeds and crosses have white legs like that, Sussex for example. The photos at McMurray's website show yellow legs. I'm not sure what is going on. You can either call McMurray and ask or, better yet, send a photo by e-mail and ask. Since they are multi-generational crosses it's very possible some of them have white legs. It would be very interesting to see how McMurray explains it.