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