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