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