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