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