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