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