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