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)(25,26,30,33)(27,31,34,38)(28,29,32,37)(35,36,39,40)(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)(28,35)(29,36)(30,34)(32,39)(33,38)(37,40)(1,2,5,4)(3,6,8,7)(10,13)(15,17)(16,21)(23,24)(27,34)(31,38)(35,39)(36,40)(9,11)(10,15)(12,20)(13,17)(14,19)(16,24)(18,22)(21,23)(25,28)(26,29)(27,35)(30,32)(31,36)(33,37)(34,39)(38,40) involution — undirected(1,2,5,4)(3,6,8,7)(9,12,14,22)(10,16,13,21)(11,18,19,20)(15,23,17,24)(25,29)(26,32)(27,36)(28,33)(30,37)(31,39)(34,40)(35,38)(1,4,5,2)(3,7,8,6)(9,13,14,10)(11,17,19,15)(12,21,22,16)(18,24,20,23)(25,27)(26,31)(28,35)(29,36)(30,34)(32,39)(33,38)(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.