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