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