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