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