On this page of our Call of the sea guide, you will find the location of all murals in Chapter 3 - The Vanishing of the lady Shannon.
Chapter 3 - The Vanishing Of Lady Shannon.
Location: at the top, in the second part of the camp.
To get to this part of the map, you need to turn on the power.
To get to the mural, you just have to climb the stairs. You'll find them in the other part of the camp. Look carefully and go to the blue symbol on the wall.