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