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