COLORS OF SALVATION
Use the Colors of Salvation EVERYWHERE. Your local dollar store has tableclothes, poster board, paper plates, etc. in the five colors. Tableclothes can cover walls, paper plates can easily be turned into stoplights & road signs.
Turn your center aisle into the main drag of town with some black rollout paper and white or yellow ducttape.
ROAD / TRAFFIC SIGNS
Each point of interest has a logo that can be used nightly. Stop signs, traffic lights, etc. all make great fillers to further convey the theme.