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