Eeeyup!

Eeeyup by *ShelltoonTV on deviantART
Oh yes, Big Macintosh is BIG alright!

This was vectored from one of those coloring pages that Hasbro put out recently. I believe these to be his official colors as they were taken from a screenshot present in the story gallery for Applebuck Season. This would definitely serve as a great color guide, or a Team Fortress 2 spray, or a T-shirt graphic, or what have you.