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