So why so blue? Well, you'd be blue, too, if you had been pancaked on the roadbed by a speeding pick-em-up or whatever it was that got this poor creature.
A photo caveat: I'm not sure whose this is, and the last photo that follows. I archive my photos to nearly museum-quality levels, with good data on species, location, date, etc., so that I can quickly find things among the gigs and gigs of images that I've got. These photos say only "Clermont County", and according to the imbedded photo-data they were taken in July 2007. I don't think they are mine, and I vaguely recall someone sending them to me in an attempt to learn the snake's identity.
Even a snake-hater can possibly be won over by one of these scaly charmers. Greensnakes are exceedingly gentle and make no attempt to bite, even when rudely plucked from hiding. They are exceptionally slender, and of the most gorgeous shade of lime-green imaginable.
This change in color begs the obvious question: why? Think back to basic art classes, when the instructor had you mix various paints to create different colors. For instance, blending the primary colors of blue and yellow makes.... GREEN, a secondary color. Mother Nature took her infinite palette of colors, and used blue pigments and yellow pigments to infuse the greensnake, leading, obviously, to its namesake tint. Upon death, the paler and less durable yellow pigment quickly breaks down, leaving the underlying blue pigment to shine strongly through. And thus, ever so briefly, we have a strange blue snake.