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