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