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