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