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