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