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