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