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