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