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