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