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