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