By trigger do you mean that the camera went off when lightning struck?
Nah, I just lowered ISO all the way down and closed my aperture to about 7.1, because I didn't want the lights to look like stars from too much diffraction. I didn't use a remote trigger, because the wind was blowing hard enough that I had to hold on to the tripod anyways.
So I basically got lucky. I'd just hold the shutter down until lightning struck and then close it immediately otherwise it would be overexposed.
It also helped that it would lightning like crazy for 20 minutes at a time. lol
I think the colors were caused by the light of the lightning mixing with the ambient light of the city.