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