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