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)(11,15)(12,14)(13,16)(19,20)(23,24)(25,26)(27,31)(28,30)(29,36)(32,38)(33,35)(34,40)(37,39)(1,3)(2,7)(4,8)(5,6)(9,10,12,14)(11,15,16,13)(18,22)(23,24)(26,28)(27,33)(32,36)(34,37)(2,8)(3,5)(9,10,12,14)(11,13,16,15)(17,18,21,22)(19,23,20,24)(25,27,30,33)(26,31,28,35)(29,37,38,34)(32,40,36,39)(1,4)(2,3)(5,8)(6,7)(9,11)(10,13)(12,16)(14,15)(17,19,21,20)(18,23,22,24)(25,28,30,26)(27,31,33,35)(29,36,38,32)(34,39,37,40)(1,5,6,3)(2,4,8,7)(9,10)(11,13)(12,14)(15,16)(17,20,21,19)(18,24,22,23)(25,29)(26,32)(27,34)(28,36)(30,38)(31,39)(33,37)(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.