adjust the colors interactively, then use the Enhanced log to get the right command ...
Next step: create your toolbar
and add a command with something like this:
Names Default to Here(1);
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
gb = dt << Graph Builder(
Size( 437, 413 ),
Graph Spacing( 4 ),
Variables( X( :height ), Y( :weight ), Overlay( :sex ) ),
Elements( Points( X, Y, Legend( 1 ) ), Smoother( X, Y, Legend( 2 ) ) )
);
wait (2);
// ^^^^^^ don't include this part ^^^^^^^^
current report() << SendToReport(
Dispatch( {}, "graph title", TextEditBox,
{Text Color( "Blue" ), Font Color( 5 )}
),
Dispatch( {}, "400", LegendBox, {Text Color( "Blue" )} )
)