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