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