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