In the false-color images scientists usually designate blue to indicate sunlight reflected at a wavelength of 2 microns, green to indicate sunlight reflected at 3 microns, and red to indicate thermal emission at 5 microns. Since the auroral emission appears to be green, this suggests emissions from hydrogen ions of light between 3 and 4 microns in wavelength. You can clearly see the contrast with the rings which appear blue and have a wavelength of 2 microns. The red, 5 micron, wavelengths you see in the southern hemisphere are due to the heat emission from the interior of Saturn.
And ok, these are not the first pictures of Saturn's aurora. Cassini has returned a number of detailed snapshots in the past. These images are more data scientists can use to understand this phenomena. Not to mention they look pretty bitchin'.
First, I highly recommend watching this short video by NASA/JPL:
And here are some story links: