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