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