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