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