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)(11,16)(12,13)(14,15)(17,18,21,20)(19,23,24,22)(25,26,30,28)(27,33,34,31)(29,36,37,32)(35,38,40,39)(2,6)(3,7)(9,11)(10,13)(12,14)(15,16)(17,19,21,24)(18,22,20,23)(27,34)(29,37)(31,33)(32,36)(3,7)(4,8)(11,12)(13,16)(17,19,21,24)(18,23,20,22)(25,27,30,34)(26,31,28,33)(29,35,37,40)(32,38,36,39)(1,3)(2,4)(5,7)(6,8)(9,12,14,11)(10,13,15,16)(17,19)(18,22)(20,23)(21,24)(25,28,30,26)(27,31,34,33)(29,36,37,32)(35,38,40,39)(1,4)(2,3)(5,8)(6,7)(9,13)(10,11)(12,15)(14,16)(17,20,21,18)(19,23,24,22)(25,29,30,37)(26,32,28,36)(27,35,34,40)(31,38,33,39)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.