I agree with what's been said re: including it in your signature is pretenious. I'm in a social science field and for what it's worth I have a few prestigious fellowships (including NSF) and am at a top 20 university. No one in my department - faculty, post doc, grad students- put any of their fellowships in their email signature.
Name
Title (e.g. PhD Candidate, Graduate Student)
Department
University
Email
It's all about presentation of self and presenting yourself as a professional (grad student) in your field