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