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