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