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