And the raw image site says:
W00074966.jpg was taken on July 24, 2012 and received on Earth July 26, 2012. The camera was pointing toward TITAN at approximately 37,059 miles (59,641 kilometers) away, and the image was taken using the CL1 and VIO filters.
I would expect any reflection to be at the bottom of this image, in line with the sun which is obviously near bottom center. That's simple optics. The color image with the "light" seems by appearance and orientation to match the left edge of the raw image, so I don't get it.
... But what do I know ???
Quite a spectacular image though.
We appear as a tiny speck from there...
In this photo by NASA's Cassini orbiter around Saturn, the planet Earth is visible as the small bright dot.