Diagram(

 Choice(0,
   Group(
     Choice(0,
       Sequence(
         Choice(0,
           Choice(2, 
             Skip(), 
             Group(Choice(0, 'whitish', 'pale', 'brilliant'), 'tint'),
             'vivid', 
             Group(Choice(0, 'blackish', 'dim', 'deep'), 'shade')
           ),
           MultipleChoice(1, 'any', Group(
             Choice(0, 
               Sequence(
                 Optional('very', 'skip'), 
                 Choice(0, 
                   'dark', 
                   'light'
                 )
               )
             ),
             'lightness'
           ), 
           'moderate',
           Group(
             Choice(0, 'grayish', 'strong', 'vivid'),
             'saturation'
           )
          )
         ), 
         Group(
          Sequence(Choice(2, Sequence(NonTerminal('base-color'), '-'), Skip(), Group(Choice(0, 'reddish', 'orangish', 'brownish', 'yellowish', 'greenish', 'bluish', 'purplish'), 'splash-color')), Group(Choice(0, 'red', 'orange', 'brown', 'yellow', 'green', 'blue', 'purple'),'base-color')),
          'hue'
         )
       )
     ),
     'chromatic color'
   ),
   Group(
     Choice(2,
       'black',
       'white',
       Sequence(
         Group(
           Choice(1, 
             Sequence(
               Optional('very', 'skip'), 
               Choice(0, 
                 'dark', 
                 'light'
               )
             ), 
             'moderate'
           ),
           'lightness'
         ),
         Choice(1, 'grey', 'gray')
       )
     ),
     'gray color'
   )
 )