Hi,
there's an interesting thread in Crustaforum regarding exactly this subject.
When you cross golden bees with red bees you get high grades but, possibly, poor white areas. I guess that your bees have golden bee genes.
More:
http://www.crustaforum.com/lhtopic,336,0,0,asc,.html
The only way to get better body color is careful selection of the shrimp with more white and breeding them on.
Takes a lot of time, place and work, but is ultimately more rewarding.
Cheers
Ulli