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