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