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