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