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