X: [A, B, C]
A: [X, K]
B: [D, X]
C: [X]
Z: [K]
K: [A, Z]
F: []
D: [B, G]
G: [D]

colors = ['RED', 'GREEN'] 

{('A', True): [('X', 'RED'), ('K', 'RED')],
 ('B', True): [('X', 'RED'), ('D', 'RED')],
 ('C', True): [('X', 'RED')],
 ('D', True): [('B', 'GREEN'), ('G', 'GREEN')],
 ('F', True): ['Any Color'],
 ('G', True): [('D', 'RED')],
 ('K', True): [('A', 'GREEN'), ('Z', 'GREEN')],
 ('X', True): [('B', 'GREEN'), ('A', 'GREEN'), ('C', 'GREEN')],
 ('Z', True): [('K', 'RED')]}