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