One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(9,10,13,16)(11,17,18,14)(12,20,21,15)(19,22,24,23)(25,26,30,31)(27,28,35,32)(29,37,38,33)(34,39,40,36)(6,8)(11,18)(14,17)(19,24)(22,23)(26,31)(28,32)(29,38)(34,40) involution — undirected(5,6)(7,8)(9,10)(11,14)(12,15)(13,16)(17,18)(19,22)(20,21)(23,24)(25,27,30,35)(26,32,31,28)(29,34,38,40)(33,39,37,36)(1,2,3,4)(9,11)(10,14)(12,19)(13,18)(15,22)(16,17)(20,23)(21,24)(25,28,30,32)(26,27,31,35)(29,36,38,39)(33,34,37,40)(9,12,13,21)(10,15,16,20)(11,19,18,24)(14,22,17,23)(25,29,30,38)(26,33,31,37)(27,34,35,40)(28,36,32,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.