Plots with shaded standard deviation
The below piece of code will generate the following Image(your's is Subplotting Three of them, so you will get 3 different axe's and per axes you have to use fill-between) (Kindly ignore the Axis Label's..)

plt.style.use('ggplot') #Change/Remove This If you Want

fig, ax = plt.subplots(figsize=(8, 4))
ax.plot(trees_grid, train_acc.mean(axis=1), alpha=0.5, color='blue', label='train', linewidth = 4.0)
ax.plot(trees_grid, test_acc.mean(axis=1), alpha=0.5, color='red', label='cv', linewidth = 1.0)
ax.fill_between(trees_grid, test_acc.mean(axis=1) - test_acc.std(axis=1), test_acc.mean(axis=1) + test_acc.std(axis=1), color='#888888', alpha=0.4)
ax.fill_between(trees_grid, test_acc.mean(axis=1) - 2*test_acc.std(axis=1), test_acc.mean(axis=1) + 2*test_acc.std(axis=1), color='#888888', alpha=0.2)
ax.legend(loc='best')
ax.set_ylim([0.88,1.02])
ax.set_ylabel("Accuracy")
ax.set_xlabel("N_estimators")