The restrooms are near the 200 wing of the building. They are designated with blue "Family Restroom" signs. Signage at the main restrooms provide a map showing the locations. They're marked on the university maps:
The restroom is in the basement near vending area. The restroom is marked "Shower".
It's marked on this map.
Morris University Center
The restroom is in the basement. Walk past Pizza Hut and Mi Cocina serving lines and around the corner.
It's marked on the university maps: http://www.siue.edu/maps/tour/pdf/MUC.pdf
The restroom is on the 1st floor of the Lukas Annex directly across from the elevator and room 1625. The restroom is designated as "Family Restroom".
It's marked on the following floor plan by a symbol of two adult figures with a child sixe figure in between them: Lukas Annex Floor Plan