Located right at the beginning of the heist. It is to the left of where you spawn inside of that room.

Located right after the first crash, to the left, there is a short wall next to a parked car, the poster is on the street side.

Down the road a bit, right next to the crane on a set of wooden walls on the right side of the street.

Right after the third poster, this poster is located on a newspaper box by the parking lot.

Right across from the fourth poster, this one is located on a double sided sign, on the burger side. It will be there even if the glass is cracked or broken, just may be hard to see.

Right before the overpass, on the right side, there is a series of yellow columns attached to the building. It will be on the last one.

After you get Matt out of the van, go all the way up the stairs. Once up there, there will be a white building and on the corner of it will be the poster. If you take the main stairway up, it will be to your direct right.

This is the final poster. The issue with this one is that it is invisible. However, it is located all the way up at the end of the overpass, next to a bench and the police barricade. It will be on the last wall shown. You will have to move around to see the interaction.
EDIT: The game has been updated to show the poster. It will be on the short side closest to the police barricade.