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