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