I think some people put too much weight on the "education" argument.
For one, as much as this will disturb the paternalists who want to think they are naturally better than everyone (ie those who can't just be in a better moral position than those they disagree with), there are a lot of degreed jobs that are just naturally biased towards certain political philosophies. Speaking firsthand as a left wing Accounting major, I can't imagine that there will be any serious trend amongst General Business types to vote Democrat. Considering how many jobs there are in business environments that involve degrees like Marketing, Advertising, Finance, yada yada it's not surprising why there is a high number of Republican graduates. And given the amount of student loan debts many have, I doubt there is that much incentive for a business grad to further their education beyond the typical "license" tests like the CPA exam or what have you. Likely, they'll just get their 150 hours down, take the test, and then call it a day. Many people don't see the point of having a Masters in Accountancy when a CPA license will make them 70% more sellable to employers at a fraction of the cost. But of course, you also need a years worth of workplace experience before you get the license so I digress.
I imagine that for fields like Liberal Arts or advanced sciences that a Masters degree or higher is a lot more of a necessity, thus probably why postgrads are so Democratic.
What I'm seeing isn't really measurement of intelligence between parties, just the difference between the parties on the economic front. A Psych major is likely going to approve more of lenient debt policies than a Marketing major because a Pscyh student is more likely going to need more debt than a Marketing student in order to get into their field.
Just my two cents.
Most basically Post-Grad jobs favor democrats because of policies. Thanks for your opinion.
In short here's what I think this would be like in an election:
Poorly Educated: Solidly Democrat
Average Educated: Lean R
Very Well Educated: Toss-Up (Which is statistically including Post-Grad)