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