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