For egg shell colors this might be handy.
http://www.maranschickenclubusa.com/files/eggreview.pdf
I find this simplistic but handy for plumage pattern and color.
http://kippenjungle.nl/Overzicht.htm#kipcalculator
There is a lot of detail in this.
http://sellers.kippenjungle.nl
Or are you...