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