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