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