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