One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(6,7)(11,17)(12,19)(15,20)(16,21)(25,26,30,31)(27,32,33,28)(29,37,38,34)(35,36,40,39)(10,14)(15,20)(16,21)(22,24)(26,31)(27,33)(29,38)(36,39) involution — undirected(5,6,8,7)(9,10)(11,15)(12,16)(13,14)(17,20)(18,22)(19,21)(23,24)(25,27)(26,32)(28,31)(29,35)(30,33)(34,39)(36,37)(38,40)(1,2,3,4)(5,7,8,6)(9,11)(10,15)(12,18)(13,17)(14,20)(16,22)(19,23)(21,24)(25,28,30,32)(26,33,31,27)(29,36,38,39)(34,40,37,35)(9,12,13,19)(10,16,14,21)(11,18,17,23)(15,22,20,24)(25,29,30,38)(26,34,31,37)(27,35,33,40)(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.