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