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)(11,16)(12,18)(13,14)(15,17)(19,23)(20,24)(21,22)(25,26,30,31)(27,33,35,28)(29,37,38,32)(34,36,40,39)(3,7)(5,8)(9,11)(10,16)(12,19)(13,15)(14,17)(18,23)(20,21)(22,24)(26,31)(28,33)(29,38)(34,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(10,17)(11,13)(12,20)(22,23)(25,27,30,35)(26,28,31,33)(29,34,38,40)(32,36,37,39)(9,12,15,20)(10,18,17,24)(11,19,13,21)(14,22,16,23)(25,27)(26,28)(29,34)(30,35)(31,33)(32,36)(37,39)(38,40)(1,3)(2,5)(4,7)(6,8)(9,13,15,11)(10,14,17,16)(12,21,20,19)(18,22,24,23)(25,28)(26,27)(29,36)(30,33)(31,35)(32,34)(37,40)(38,39)(1,2)(3,5)(4,6)(7,8)(9,14)(10,11)(12,22)(13,17)(15,16)(18,19)(20,23)(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.