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