Until now, only the guests got different colours when they entered. In the original game, many more things could have a different colour, amongst others, the shops.
FreeRCT did have a notion of recolouring for quite some time, but either the graphics didn't allow use of it, or it was not really working.
Today, I committed a set of patches that should fix all that. The 32bpp blitter now also does recolouring. I have also added a dropdown to allow selecting a new colour if the random colours are not to your liking.
Last but not least, there is a new shop, the ice cream stall. It's a 32bpp sprite, and as you can see, it comes in all (re)colours.