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