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