Green, yellow, orange, and red LEDs are narrow line width sources. They should reproduce fairly accurately on color film, although the brightness may not be the same as you see with your eye. You can make a fair guess by looking at the published sensitvity curves for the film. Blue, violet, and "true green" LEDs have braoder spectra. They will still probably look OK, but you could get some funnies. White LEDs are usually a combination of a blue LED and a yellow phosphor. The emitted light is really quite blue. Most produce a decent white source light for daylight film, but some show maked dropouts in certain colors.