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