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