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