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