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