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