I’m not sure if this was a recent addition but the docs here
mention you can do something like
import onnx

# Load the ONNX model
model = onnx.load("alexnet.onnx")

# Check that the IR is well formed
onnx.checker.check_model(model)

# Print a human readable representation of the graph
onnx.helper.printable_graph(model.graph)