What significance does color of CAT 5 play?

Answer 1

There is no difference between yellow, blue, gray, or black. What matters is if there is a letter after the number? Such as cat5e. That's where your ratings come in.

Answer 2

if your asking about the multi-color wires in the cable they are to id the order in which you crimp the cable connector unless your making a comm cable and if you don't understand this answer your better off buying your cables pre-fab