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