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