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