I haven't figured out a way to set the color back to normal after using set color.
You can use replace color effect instead of set color. This allows you to find specific colors on specific Object Sprites and change just those colors and then change them back.
Mark the RGB values you have in your effect properties, then using the event sheet set your parameter 1 (replace) value to the color you want.
Enable it when you want to change colors - disable when you want to go back.
If you want more information this video goes over Replace Color
youtube.com/watch