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