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