My best advice on choosing babies for optimum color would be to know your breeder and be able to look at the parents of the baby - but even that is no guarantee. It does improve your odds though, with another option being to buy an adult or young adult snake instead of a baby - so you know what you are getting. That is what I would do if color was especially important to a breeding program. If it is just a color preference, you will likely find that you really like whatever your baby snake grows up to look like.
On mouse breeders - just be aware that there are two operations with Mouseman in their name in Canada - the Canadian Mouseman in Medicine Hat Alberta and the Mouseman in Victoria, BC. My comments above apply to the Canadian Mouseman. I have actually purchased from Ian, the Mouseman (because he has rats as well) and he is really great to deal with. Good prices, although the shipping cost on rats would really be a killer if they had to go from Victoria to Newfoundland.
best of luck,
mary v.