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