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