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