I found this british website that explans that there are many color gene factors. This is an excerpt from the website that I think will help you.
Poultry Genetics
The problems and interesting facts about breeding poultry
Egg Colour
is determined by the genetics of the parents
The genes involved are unlikely to be in a simple relationship but some basic principles can be seen. If one breeds birds with white eggs to those with brown then the pullets produced lay a variety of tinted eggs. It is possible that there are factors for amount of colour - the white layer has none of the extra colour factors and a dark egg layer has most extra factors. It is also possible that there is an inhibitor factor as well to inhibit colouring.
It is known that the colour is sex linked - i.e. that the father is the most important determinant for the colour of the eggs in the next generation.
Therefore your cockerel/ drake is the most important bird in controlling and improving your egg colour in the future.
The other very important factor is yourself - you chose the eggs that are hatched - you control the quality of the next generation.
only hatch eggs that are of a good size for the breed
never hatch eggs that are the wrong colour for the breed
if you have a number of birds laying roughly the right colour - choose the best and be hard with your selections
if you have eggs that are not correct replace the breeding cockerel with one hatched from the correct colour and size
Every time you hatch (or if using broody hens allow to be hatched) chicks /ducklings that are from eggs that are not right for the breed - come from hens that are not productive - etc you are playing a part in the demise of utility strains.
Chickens:
White :- Leghorns; Minorca
Mid Brown - Rhode Island Red; Orpington; Wyandotte; Sussex:
Dark Brown - marans; welsumer; Barnevelder
Blue - Araucana; Cream Legbar
WHITE :
If you have a white egg laying breed and you are getting some creamy eggs there are several actions you can take:
do not hatch any of the creamy eggs
replace the cockerel with one hatched from a white egg
BLUE
The blue egg colour of the Araucana is a dominant gene - so when the Araucana is crossed with another breed - the female offspring will always lay blue or tinted eggs
This might be useful for the immediate future while the Araucana is not a particularly eggy breed these days but the demand for blue eggs at farmers markets for example is rising fast.
- By crossing with a white egg layer from a really good laying strain it may be possible to produce a hybrid layer pullet with a good blue egg.
- This would allow breeders to produce a much larger number of blue egg laying pullets for the laying market;
- allow the best pure breed hens (most eggs of the required colour)to be kept in the pure breeding units
- and increase the value of the cockerels bred from good blue eggs for hybrid production as well as pure breed lines
- The cross bred pullets would not be for breeding from but by working hard at the same time to produce better and better parent stock each offspring hatch should improve.
http://www.utilitypoultry.co.uk/eggcolour.shtml
Hope This helps!