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