How to create only one copy of graph in tensorboard events file with custom tf.Estimator?

You need to use the TensorBoard tool for visualizing the contents of your summary logs.

The event file log can be read and use it.
You can see the example from this link provides information about how to read events written to an event file.

# This example supposes that the events file contains summaries with a
# summary value tag 'loss'.  These could have been added by calling
# `add_summary()`, passing the output of a scalar summary op created with
# with: `tf.compat.v1.summary.scalar('loss', loss_tensor)`.
for e in tf.compat.v1.train.summary_iterator(path to events file):
    for v in e.summary.value:
        if v.tag == 'loss':
            print(v.simple_value)