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