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