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