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