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