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)(11,17)(12,18)(13,21)(14,15)(16,22)(19,20)(23,24)(27,33)(31,34)(35,39)(38,40)(1,3,4,7)(2,5,6,8)(10,15)(12,17)(13,22)(19,24)(25,26)(27,31)(28,36)(29,30)(32,37)(33,34)(35,40)(38,39)(1,2)(3,5)(4,6)(7,8)(10,15)(11,18)(16,21)(19,24)(26,30)(31,34)(32,36)(38,40) involution — undirected(9,11,14,18)(10,12,15,17)(13,19,22,24)(16,20,21,23)(25,26)(27,34)(28,32)(29,30)(31,33)(35,40)(36,37)(38,39)(1,3)(2,5)(4,7)(6,8)(9,12)(10,11)(13,20)(14,17)(15,18)(16,19)(21,24)(22,23)(25,27)(26,31)(28,35)(29,33)(30,34)(32,38)(36,40)(37,39) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,13)(10,16)(11,19)(12,20)(14,22)(15,21)(17,23)(18,24)(25,28,29,37)(26,32,30,36)(27,35,33,39)(31,38,34,40)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.