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