I'm not the author of the original concept of those axes. They were circulating online in form of a picture without a watermark – making it practically impossible to find the author. I just made an interactive version of it, with a few adjustments.
I'm aware that this representation of gender & sexuality is not perfect – but none is! Humans are more complex than just a few axes!
Yes, us nonbinary folks aren't necessarily in between “male” and “female”, yes, lumping bisexuality and pansexuality together is not ideal, etc. etc. etc. But it's an approximation. If you come up with a better one, I'd gladly make an app for it 😉