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