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