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