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