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