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