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