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