I think that the trans community or even subgroups within it are diverse in a way many others aren't. Of course, there's a huge part of it that is just the random chance of being born trans, so that it's much like the community of type-1 diabetics. In fact, it's a lot like that: a bunch of people whose endocrine systems are seriously messed up, and who must look to medicine and pharmeceutical companies in order to get by, but otherwise, totally uncorrelated with anything else.
The other side of it is that being trans forces you to think about gender, and with it some very deep questions about identity and society. And people come to very different conclusions, because the experience itself seems to be rather different from person to person.
I think that the gay and lesbian communities would be similar, but they are so much more cohesive -- when you are gay, you want to hang around other gay people, but trans people don't have any particular reason to be friends.
So trans people have little holding us together, have much more significantly similar yet extremely diverse experiences that define our community, and are as inherently deverse as any randomly selected group. There aren't a lot of groups that have those attributes. The only ones I can think of are tragic.