If your looking for a city map that is already built and ready to use, you won't find one, as far as I'm aware. Haven't played Milf City, but the map in Summer Time Saga, is drawn. So to semi-answer your question. You can
1. Get or make the 3D models of the buildings, roads, trees, misc and construct them all together and take a snapshot from the top view or which ever angle you prefer.
2. Draw the city map