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