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