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