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