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