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