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)(11,19,22,13)(12,23)(14,29)(15,18)(16,26)(17,24)(20,33,36,39)(21,28,34,32)(25,35,31,40)(27,38)(30,37)(2,6,8,7)(9,11,13,18)(10,15,22,19)(12,20,25,30)(14,21,28,29)(16,27,36,31)(17,24,34,32)(23,37,40,33)(26,35,39,38)(9,12,24,37,15,27,14,26)(10,16,29,38,18,30,17,23)(11,20,34,40,22,36,21,35)(13,25,32,33,19,31,28,39)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.