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