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