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