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