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