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