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