I'd be really interested to see the specifics of how that data is collected, but also fucking duh recent college grads are underemployed. Also, having that degree sets people up for career advancement as they gain experience and that educational background becomes even more of a prerequisite for the jobs they're moving into
If you are employed in a junior job within the field you have been trained in, you are not underemployed.
What this graph shows however, is that there are a ton of degrees that seem to teach hardly any transferable skills. A sociologist without proper statistical training has almost zero value in the business world. And that's a problem.
That's why I explicitly qualified my statement, because not all sociologists are in fact trained in statistics. Many just had the statistics 101 class and went into the more philosophical part of the trade.
The real question is: what else does this graph show in your interpretation?
I interpret it as there are more degree holders than there are jobs that closely align with that degree. Graduating art history majors are absolutely qualified to be curators at galleries and museums, but there are only a handful of those positions available.