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