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