There is a tool to change the color pallet used in certain levels. You could have the world get progressivly dartker as you approach the lady, representing time passing and christmas approaching.
You click on the plus icon here (red) and then you can edit the pallet. Using the arrows you can change betwen each pallet to edit them.
You simply presss the plus icon located at the bottom of your color window to add a new color pallet. You can edit each individually by pressing the arrows.
Once you are happy with your pallet, you can continue to change it on the bottom of your room window, click on the onlty button to show the tools for the room, then at the very bottom you will be given the chance to change the color pallet of the especific room.