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