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