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