I did this for my sister's birthday. Chitty Chitty Bang Bang was a childhood favorite. The face transplant, if you will, wasn't so hard, but getting the splashes of color in there was challenging. The Selective Color adjustment was the easiest and most helpful, and the Hue/Saturation adjustment helped tone it down. I had to create new layers for each colored piece; I'm sure there's an easier way, but I don't know of one.
Original Chitty Chitty Bang Bang picture.
Original picture of my sister.