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