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