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