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)(11,19,21,15)(12,24,25,39)(13,16)(14,18)(17,26,30,34)(20,27)(22,36)(23,32,33,29)(28,37)(31,40)(35,38)(1,3,4,7)(2,5,6,8)(9,11,20,33,13,21,14,23)(10,15,27,32,16,19,18,29)(12,22,34,40,25,35,26,37)(17,28,39,36,30,31,24,38)(3,7)(5,8)(10,16)(11,21)(15,19)(18,27)(22,35)(23,33)(29,32)(37,40) involution — undirected(9,12)(10,17,16,30)(11,22)(13,25)(14,26)(15,28,19,31)(18,24,27,39)(20,34)(21,35)(23,37)(29,38,32,36)(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.