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