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