Randomly Shuffle and Periodically Re-Shuffle a list?

I am working on an Arduino project, via Firefly, where I want to color code someone's distance from a sensor by using Blue, Green and Red LED's that sequentially illuminate at designated distances from said sensor.  When touching the sensor, the only LED still illuminated will be the Red one.  However, I would like this relationship to change every five minutes or so, so that the color illuminated at the closest distance is not always predictably Red.  

Is there a way to have a list of three items randomly reorder itself every (x) minutes?