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