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