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