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)(13,14)(15,18)(16,21)(19,22)(23,24)(26,31)(29,33)(32,38)(36,39) involution — undirected(1,2)(3,7)(4,8)(5,6)(9,10)(11,17)(12,16)(13,14)(15,18)(19,23)(20,21)(22,24)(25,26,30,31)(27,32,37,38)(28,29,34,33)(35,36,40,39)(10,14)(11,18)(16,20)(19,24)(26,31)(28,34)(32,38)(35,40) involution — undirected(1,3,5,4)(2,7,6,8)(9,10)(11,15)(12,16)(13,14)(17,18)(19,22)(20,21)(23,24)(25,27,30,37)(26,32,31,38)(28,35,34,40)(29,36,33,39)(9,11,13,18)(10,15,14,17)(12,19,21,24)(16,22,20,23)(25,28,30,34)(26,33,31,29)(27,35,37,40)(32,39,38,36)(1,4,5,3)(2,8,6,7)(9,12)(10,16)(11,19)(13,21)(14,20)(15,22)(17,23)(18,24)(25,29,30,33)(26,34,31,28)(27,36,37,39)(32,40,38,35)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.