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