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