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