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