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