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