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