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