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