Set up conversations near the end of your internship with people at the company about your future career path. You might be able to continue your internship work in some capacity, and many companies will have full time openings in the future that they will be excited for you to apply to.
Talk with internship mentors and supervisors, because they most likely have contacts at other companies in the industry or related fields. End each conversation by asking “who else do you suggest I talk with?” That is a great way of getting connected to new people.
Connect with alumni from your university, especially from your department. Talk with your graduate program director about your career aspirations – they probably know a list of alumni working in industry and could help you connect with those alums.
Check your campus online job board, where career fairs are advertised and employers seek applicants from your university specifically. Register for the job board, put the career fairs on your calendar, and look regularly for new job postings.