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