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