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