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