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