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