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