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