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