On the job, you may come in contact with other students, staff, and visitors. It's important for you to remember that, as an employee, you represent your department and the university. This is a state-operated institution, and with that goes a responsibility to treat the public with due respect and consideration. You will be working with career employees, and there are definite and real functions that need to be fulfilled. The level of decision-making and authority that you are assigned will match not necessarily your potential, but instead, the job description of the position in which you have been hired.
Demeanor is behavior.
Hence, learn to behave like an expert in the position into which you've been hired, regardless of its required skill level or your future goals. Look to your supervisor for guidance. There is no campus-wide dress code. However, it can be said that you are not expected to compete with your supervisor or department head regarding attire. You are expected to dress neatly, cleanly, and within reasonable limits appropriate to your work environment.