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