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