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