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