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