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