Hi there,

Public form draft url should be retrievable through url

        ...form/resume/{formId}/{submissionId}

where {formId} is the form id you can see in the form designer in your starting form, and,

{submissionId} can be queried in your Forms database

select * from cf_form_submissions where process_id  in (select process_id from  cf_bp_processes where bp_id = {your_business_process_id})

{your_business_process_id} is the id you can see in the url of your process modeler

Note that you will not be able to view the draft unless you have password set by the public user when it was created 

Thank you.