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