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