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