This was quite a hassle to arrange the layers but it should work now.

Info:
This features both a male and female version. The one that is activated now is the male one, if you'd like to color in a mare, just make the upper three layers invisible and activate the next three which say "mare".
The names of the layers should make it clear where you need to color (don't forget to lock alpha when you do!). Mane & body, for both genders, are on two seperate layers so you have an easier time coloring it in. The eyes and tongue are on a seperate layer so you don't need to color those, you can basically ignore them, they won't change when coloring the rest. ^^
Also, you might've noticed that the color layers are set at 75% opacity. I set it so low because otherwise, if you use dark colors, the lines won't really show. Of course you can change the opacity if you like, I just thought it looks better when the lines are fully visible, at least for darker colored 'quids. In case you choose to leave the opacity at 75%, and would like to use it as a transparent version in your siggy or somewhere, don't worry about the background color (for example the light grey in CS signatures) shimmering through - I added a white base to avoid that. That layer can be ignored, too. C:
I left the "Derp!" on but of course you can remove it or change it to whatever you wish. I also left a white background layer that you can activate if you don't want a transparent version. You're free to do whatever you wish with that one.
If you'd like to color it in, just post here with a proof of your ownership and I'll add you.

The only rules I have are:
Please don't touch the signature, don't alter the lines & give me credit when someone asks/you use it off-site/things like that.
Other than that, enjoy coloring and spread the derpness! ^__^
(c) Artwork - Me
(c) WME species - horsy1050