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)(25,26,31,36)(27,33,38,40)(28,39,37,32)(29,34,30,35)(1,3,5,4)(2,6,7,8)(9,11)(10,14)(12,19)(13,17)(15,23)(16,21)(18,20)(22,24)(25,27,29,28,31,38,30,37)(26,32,35,40,36,39,34,33)(11,17)(14,21)(18,19)(22,23)(25,28,29,38,31,37,30,27)(26,33,35,32,36,40,34,39)(9,12,13,20)(10,15,16,24)(11,18,17,19)(14,22,21,23)(25,29,31,30)(26,34,36,35)(27,37,38,28)(32,40,39,33)(1,4,5,3)(2,6,7,8)(10,16)(14,21)(15,24)(22,23)(25,29,31,30)(26,35,36,34)(27,37,38,28)(32,33,39,40)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.