The Student Association of the Computer Science Department at Saarland University organizes a short guided tour for newcomers (German: "Orientierungseinheit") around the university campus, but this tour is in German.
If you’d like a tour in English, ask for the dates the "Zis-Info-Point" in building A 1.7
(on the campus map), ground floor, room E3.3.
More information: Studying at Saarland University