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