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