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