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