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