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