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