Multiple distance sensors with multiple led strips

I'm looking to build an installation using distance sensors which turn strips of LEDs from red to Blue depending on how close people are to it (red when close, blue when far away) my problem is I want 8 pairs of distance sensor and LED strip combo which can be individually addressed and recognised by an arduino. Could the arduino work out which sensor was being activated and light up an individual LED strip. I think I'd need about 40 pins so an arduino mega would seem the way forward but is this even possible?
I'm no massively experienced with arduino and coding but I'm very proficient in Max/MSP which I'll use to recieve the distance values and effect audio. Just to give you a measure of my experience.
Thanks in advance.

What sort of distance sensor?

How did you arrive at the value 40?