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