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