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