Well, the most "low-tech" way (which usually means low-cost) would be to hang lights to illuminate it externally. Some painstaking
shutter cuts and some clever cueing can make the panel change color before your very eyes.
Alternatively, if you've got some capital at your disposal you can hang less lights and add scrollers or other types of color changers. I would discourage
LED if you are front lighting as it is difficult to control the
spill of this type of light. You can use LEDs if you are lighting a fabric/plexi panel from the rear because you can
build the panel to
block light from escaping around it.
Side note: A fiber optic curtain would give you the illusion of a starry night sky. Fiberoptics carry light
thru plastic "tubes" to a surface. The light is only visible
thru the end
point of each "tube". You're thinking of an
LED curtain that would glow like that.
Good Luck