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