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