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