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