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