The picture has that brownish vintage look all around. Even the white of the eyes is kinda brownish. Her eyes are still very bright.
The same effect happens in this picture
Also, with Colleen's centerfold close in color tone and brightness to Lynda's centerfold, like in this pic, her blue eyes also look hazel.
If anything it's even more evidence that it's legit, IMO. Because if someone was to fake it, they would definitely make her eyes blue.