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