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