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