Hi, on a default layout you can change the colour of the walls by changing either the "themes" or shooting at the outer square line on the top (beyond the center).
But when you "move" the walls closer to you - they are of the same gray-ish colour and there's no way of making the bots more visible, especially when you also add boxes.

So my suggestion is to add the ability to change the colour of ALL the walls on the map, not just the ones that are there when you just loaded the map.