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