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