After a little searching, I found a Fox News poll (conducted Aug 11-13) that gave breakdowns for some groups. Trump got more support among men than among women (28% to 21%)*. I don't think anyone will be surprised at that, but the difference is smaller than I would have expected. Women generally are less attracted by "toughness" or "outsider" appeals, and when you add Trump's various offensive comments, it seems surprising that the gap isn't bigger. 27% of evangelical Christians supported Trump; they didn't give numbers for non-evangelicals, but he got only 25% support overall. So in this poll evangelicals were somewhat more likely to support Trump than non-evangelicals, but given the size of the sample I'm sure that the difference isn't statistically significant. For age and income, there's no evidence of a difference. Education, however, makes a big difference: Trump got 30% support from people without a college degree and only 18% from those with a college degree. So clearly some candidate did better among people with college degrees: who was it? The obvious answer is the establishment candidate, Jeb Bush, but Bush was at 10% among people without a college degree and 8% among people with a degree. The ones who actually did better among people with college degrees were Ben Carson (16% to 8%), Marco Rubio (7% to 2%), and Scott Walker (8% to 4%). Apart from Trump, the only other candidate who did noticeably worse among the college-educated was Ted Cruz (8% to 12%).
The differences by education are intriguing--Rubio and Walker can be regarded as establishment candidates, plus Rubio has tried to cultivate an image as a serious policy thinker, but Carson is just as much of a populist and outsider as Trump. One possibility is that the desire for "diversity" is stronger among college-educated voters, but then the numbers for Cruz are a puzzle. (There's also Bobby Jindal, but he gets virtually no support among any group, so we don't have to worry about him).
The margin of error in group differences from a single poll is large, but the association between education and support for Carson bears watching. Every story about Bernie Sanders seems to point out that his supporters tend to be well educated. According to the same poll, Sanders gets 37% among likely Democratic primary voters with college degrees, and 26% among those without. So in a relative sense, Carson's support is more concentrated among college graduates than Sanders's is.
*The figures refer to likely Republican primary voters.