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)(25,26,32,38,31,37,30,36)(27,35,39,34,29,33,28,40)(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)(26,33)(28,30)(29,31)(32,39)(34,36)(35,37)(38,40) involution — undirected(2,5)(6,7)(11,18)(14,17)(19,24)(21,23)(25,28)(26,34)(27,32)(29,30)(31,39)(33,38)(35,36)(37,40) involution — undirected(1,3,4,8)(2,6,5,7)(10,15)(11,18)(16,22)(19,24)(25,29,31,27)(26,35,37,33)(28,30,39,32)(34,36,40,38)(9,12,13,20)(10,16,15,22)(11,19,18,24)(14,21,17,23)(25,30,31,32)(26,36,37,38)(27,39,29,28)(33,40,35,34)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.