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