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