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