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)(11,15)(12,24)(13,27)(14,17)(16,21)(18,22)(19,25)(20,28)(23,34)(26,40)(29,38)(30,37)(31,35)(32,39)(33,36)(1,3,5,4)(2,6,7,8)(11,20)(15,28)(16,31)(21,35)(23,37)(29,32)(30,34)(38,39)(1,4,5,3)(2,6,7,8)(10,15)(11,21)(12,22)(13,25)(16,18)(17,28)(19,34)(20,35)(23,39)(24,29)(26,36)(27,30)(31,33)(32,40)(37,38)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.