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