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