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