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