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