Sure, simply create masks and use duplicates of your layers to colorize individual parts differently.
Or spend a few horus researching Day For Night, also known as DFN. The subtle aspects of this craft are quite complex and if you did not plan for many of them before shooting you may be completely out of luck. There is a huge difference between a DFN look and an effect that will sell the audience. For instance, someone wearing sunglasses in a shot or hard shadows caused by direct sunlight can turn your carefully crafted day for night shot into nothing more than a cheap blue overlay.