^That would be a good question that no one has asked, nor has it been mentioned by anyone at the park.
I would have guessed if they were able to choose the colors I would have expected gold and tan, but since Williamsburg was a little more strict about color choices we've been stuck with the dual-blue. Must admit I wasn't totally sold on the blue colors at first, but with the "thought process" of it representing the sky and the golden train being the actual griffon it works out. Not to mention when seeing it in person it does look very nice in the area.