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