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