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