From the I-10 west (Papago Freeway), take the Highway 85 exit south. Head south on Highway 85 for 37 miles towards Gila Bend. Then take I-8 towards San Diego for 13 miles to the Painted Rock Dam Road exit (exit 102). Take Painted Rock Dam Road 15 miles north and bird at different stops along the way (the campround is at 11 miles).
Map # 2: A closer overview of Painted Rock Dam Road and Painted Rock Reservoir.