Color of the bird, anywhere(color of legs is another very common but mistaken claim), has no effect on the egg color. Egg colors is due to GENES specifically for eggshell color. So a white hen can lay white, brown, really dark brown, blue, green etc.. just depends on what she has in regards to genes specifically for the eggshell color.
There are many genes for eggshell color, the various shades of brown & tan eggshells especially tend to have several different genes that affect the shade/intensity of the tint.
Speckled asked if the hen laid blue(OR green) because there is just one gene for what makes the eggs "blue or green" and it is a dominant gene. In other words, if she lays brown or tan eggs, she lacks the gene so this cross will produce all daughters that lay brown or tan eggs- no blue or greens.
IF she lays blue or green eggs, it shows she has the gene. Remember it is a dominant gene which means the cross will produce daughters that lay blue or green eggs.. it could be half of the daughters, if the mother had only one copy of the gene.. ALL of the daughters will if she had two copies.
The gene for blue and green eggs is due to the same gene.. the difference is what other genes the hen has- if she has genes for lighter eggshells, then her eggs will tend to be blue-bluish.. if she has genes for brown or darker eggshells then the eggs will be green. It's a visual combination of the blue and brown you're seeing on the green eggs.