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