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