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