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