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