check this out:
import matplotlib.pyplot as plt
import numpy as np
fig, ax = plt.subplots()
scatter_x = np.array([1,2,3,4,5])
scatter_y = np.array([5,4,3,2,1])
group = np.array([1,3,2,1,3])
for g in np.unique(group):
i = np.where(group == g)
ax.scatter(scatter_x[i], scatter_y[i], label=g)
ax.legend()
plt.show()
