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