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