I think this coloring page would look great with varying shades of blue and red to depict Spider-Man's costume. Bright or metallic colors could be used to highlight the iconic spider symbol on his chest. The eyes should be a bright white, with a deep black for his pupils. For the Lizard, I would suggest using a mix of muted green and black colors to create a striking pattern of spots across his back. To make him look especially menacing, use a darker green along the edges of his claws and a darker black for his tail. Lastly, use a lighter shade of green for his forked tongue for a mastery touch.