I noticed that the colors of the wires in the book and in the actual package can vary. It doesn't matter, the color of the wire doesn't really mean anything.
However, I'd use the same color for the same purpose. For example, if I wanted to connect 3 LEDs to pins on the Uno board, those three connections would all be used with green wire. Then, if I send a wire from the input pin on the Uno board to the breadboard I would use yellow, or something along the lines of that.