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