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