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)(25,26,32,40,31,35,30,29)(27,34,37,33,28,39,38,36)(1,3,4,8)(2,5,6,7)(11,17)(12,20)(14,21)(15,19)(25,27,31,28)(26,33,35,36)(29,39,40,34)(30,37,32,38)(2,6)(5,7)(9,11,13,17)(10,14,16,21)(12,18,20,23)(15,22,19,24)(25,28,31,27)(26,34,35,39)(29,36,40,33)(30,37,32,38)(3,8)(5,7)(11,17)(14,21)(18,23)(22,24)(25,29,32,26,31,40,30,35)(27,36,37,34,28,33,38,39)(9,12,13,20)(10,15,16,19)(11,18,17,23)(14,22,21,24)(25,30,31,32)(26,29,35,40)(27,37,28,38)(33,39,36,34)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.