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