Three copies of the Clebsch Graph can cover $K_{16}$, the complete graph on 16 vertices. This is part of the demonstration that $\mathrm{Ramsey}(3,3,3) > 16$.
The Hoffman–Singleton graph is a (7,5)-cage, and is one of the more famous graphs in graph theory. Can 7 copies of this graph cover the complete graph $K_{50}$?