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