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