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