@OP-
I think if you use this chip: PCA9685 chip.. you would not need to use the transistor(s) anymore...no? As the driver chip woudl supply each 'output pin' with 25mA for that 'led'...
going this route (as mentioned) gives you the flexibility to make each wall a color of your choice.. where are transistors is limiting you to the same color for ALL walls..