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