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