Gender is a spectrum, but trans just means not cis, with cis meaning identifying with your assigned at birth gender.

Cis and trans are Latin prefixes and opposites of each other - cis basically translating out to "same" and trans being "different." To be cis means to be the same gender that the doctor assigned you when you were born, while trans people transition to a gender different from their assigned gender. So you can't be on a spectrum of more trans or less trans because you're transitioning to x, y, or z.

There are spectrums that people choose from, though, if you want to get into some of the finer details. Some people use the prefix demi, meaning "partially" (like in demigod), to signify a gender that they most closely relate to but don't feel properly identifies them. Like somebody who is a demigirl most closely relates to being a woman, but doesn't feel like womanhood fits them. This is why the umbrella term non-binary exists, for people who feel like they fall somewhere outside the traditional designated roles of "man" or "woman" and more closely relate to a secret, third thing.

I don't know if you could call it a spectrum, but there are certainly more types of transgender people than cisgender. MTF, FTM, gender fluid, non-binary, and maybe even more. I wouldn't say there are degrees of transgenderism, tho. You are or you aren't.

Sexuality, on the other hand, is definitely a spectrum.