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