That's never the case with data visualization. Explanation helps remove ambiguity, and the lack of explanation behind the data source is why there is an excessive amount of criticism in the HN comments.
Regardless, the graph does not certainly speak for itself. There's no obvious correlation between which professions have a better gender pay split than others. If you're trying to make the point that most professions pay women less than men, then you need to justify that. (And provide evidence that the chart represents "most professions.")