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