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