I think by leaving the chain all one color, you make a strong diagonal line. If you mixed it up, you might lose the impact of the design.

But by all means, play around with it.

It looks great the way it is and it would also look great if you wanted to go totally scrappy with it. It would be awesome that way.
peace

I really like this pattern ! You could do it more scrappy, but I am not sure it would have the same look. If you do, please post a picture so we all can see. Thanks for bringing it to my attention:)