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