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