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