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