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