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