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