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