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