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