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)(27,34)(28,29)(30,32)(31,33)(35,39)(36,37)(38,40) involution — undirected(1,2,4,5)(3,6,7,8)(9,10,14,11)(12,17,19,15)(13,16,21,18)(20,23,24,22)(27,28)(29,34)(35,36)(37,39)(2,5)(6,8)(12,19)(15,17)(20,24)(22,23)(25,27,31,28)(26,29,33,34)(30,35,38,36)(32,37,40,39)(3,7)(6,8)(9,11,14,10)(12,17,19,15)(13,16,21,18)(20,22,24,23)(25,28,31,27)(26,29,33,34)(30,35,38,36)(32,39,40,37)(1,2)(3,6)(4,5)(7,8)(9,12,14,19)(10,15,11,17)(13,20,21,24)(16,22,18,23)(25,29)(26,27)(28,33)(30,37)(31,34)(32,35)(36,40)(38,39)(1,3,4,7)(2,6,5,8)(9,13,14,21)(10,16,11,18)(12,20,19,24)(15,22,17,23)(25,30,31,38)(26,32,33,40)(27,35,28,36)(29,37,34,39)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.