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