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