Pure monkey business!
“By visual analogy, the Capuchin monkey and the cappuccino style of coffee are both named after the shade of brown used in the Capuchin Monk habit.”
Capuchins were named after capuchin monks because the dark fur that forms a cap on their heads and extends down in ‘side-burns’ resembles the cowl or headdress of the priests.
Actually, Capuchins are friars, not monks. They are one of the three branches of the first order of St. Francis (the Franciscans).