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