Example pandas plotting by label

plotting_example.py

import pandas as pd
import matplotlib.pyplot as plt

# obtain example dataset
iris = pd.read_csv('https://raw.githubusercontent.com/mwaskom/seaborn-data/master/iris.csv')

# get the matplotlib default color cycle
cycle = iter(plt.rcParams['axes.prop_cycle'].by_key()['color'])

# use pandas to plot by label
ax = None
for species, group in iris.groupby('species'):  # group is a sub-dataset consisting of each "species"
    ax = group.plot.scatter(
        x='sepal_length',
        y='sepal_width',
        c=next(cycle),   # specify color
        label=species,   # specify legend label
        ax=ax)           # update same axes object

Replace iter with itertools.cycle if you expect more than 9 colors/labels.