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