Use Matplotlib, Seaborn, or another installed Python plotting library for static charts. Displayed figures are returned as rich notebook outputs, and saved files are available through artifacts or normal filesystem reads. 
result = machine.run_code("""
import matplotlib.pyplot as plt

plt.figure(figsize=(4, 3))
plt.bar(["A", "B", "C"], [3, 7, 5])
plt.title("Example chart")
plt.tight_layout()
plt.savefig("/workspace/chart.png")
plt.show()
""")

png_outputs = [
    item for item in result.results
    if item.png or (item.data and "image/png" in item.data)
]
print(len(png_outputs))
Rich result objects (item.png, item.data) are SDK-only. Via the CLI or HTTP API, save the figure to a file (as above) and fetch it with code artifact download or a filesystem read. Download a saved chart from the machine: 
chart_bytes = machine.files.read("/workspace/chart.png", format="bytes")