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