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