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