To help craft your thoughts, you should consider why the students would think you're important.
If you have no connection to them or can't figure out if you would impress them by your profession, then keep the remarks short and inspiring.
Example..... my high school graduation speaker was then-Representative Floyd Flake (before he became an Alpha). The seniors had nothing to do with inviting him to speak. Our parents sorta groaned when they heard it would be him. I can recall nothing that he said other than the general feeling I had of not being impressed.
Truthfully, I am not sure if anyone I know remembers the content of their 12th grade commencement speaker's speeches.
Anyway, to reiterate....just make it general and short and you will be appreciated -- in hindsight, I don't think a graduation speaker would have taught me anything that my teachers, mentors, and family hadn't already.