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