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