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