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