Yeah you can still do it in keyboard mode, but have to toggle it manually when you want to see it specifically. You're actually wanting to switch to mouse mode to put your cursor over the thing to keep the hover range visible?!
I don't currently plan to add this particular permanent view to the map, though, for various reasons. If it was going to happen it would've been done ages ago, but there is too much variety in terms of the circle sizes there and it could interfere with more important info. The precise edges of the sensor range are much less important or reliable than, say, FarCom and others because it's not real-time info.
This is something that could
theoretically be added one day, but most importantly can't be added now because it might need to be
removed one day, and that's something that you don't want to do in a game wherever possible
So for example this could be added at the very end of development if it's still feasible.
