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