This is a biased, but honest observation that I'd like to share. I've been working for a big corp for about 5 years now. I was born in a SE Asian country and came to the US for college. I have worked with a lot of India-born people.
As a fellow foreigner and as an Asian, I can tell that more often than not Indian people are bolder and more aggressive in asking for what they want (e.g., one of my Indian colleague asked for salary raise and the permission to go back to India in December for a month every year as part of his negotiation when he applied and got offer from another company; what he told me was simple, "It's my responsibility to ask. It's my boss' task to refuse or accept.") On top of that, some (not everyone; some are meek/introvert like myself). Because of their boldness, Indian people seem to be more successful at making themselves more visible, which is very important in corporate culture to get ahead. On top of that, some of them are pretty clever at courting favor of their superiors and/or playing office politics. I have seen quite a few of my peers/acquaintances from India who climbed corporate ladder pretty fast, so I'm not surprised they are doing well in terms of representation in C-level roles.