There were bright bursts of color in a concentrated area of cloud for a couple of minutes.

My sister and I were walking over to the neighbor's to feed their pets while they were on vacation.  We lived in the country at the time so there were few houses around us.  As we walked along the gravel road to their house, we looked into the sky at about a 60 degree angle.  It was very cloudy so that the sky couldn't be seen.  However, in the clouds, there were a bunch of color bursts.  It went on for a minute or two, in a very limited area of the clouds.  There were green, blue, orange, yellow, and pink bursts.  They didn't follow any pattern as to location in the area of cloud or the series of colors.  We didn't think it was any sort of lightning as the weather didn't feel like thunder and lightning weather at all. We watched it until it stopped and then fed the neighbor's pets.
 
Date is approximate.  PD