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