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