Hi Eric,
Are you using SharePoint 2010 workflow platform or SharePoint 2013 workflow platform?
If you are using 2010 platform, you can customize the InfoPath form via clicking Approval_xxxx_xxx.xsn under Forms like the screenshot:
Or, you can add ["%Current Task:Form_URN%]&Source=http://sharepoint/sitename" to the email notification body. After that, when the approver click the link in the email to approve, after approving, it will redirect to the source page.
More information:
http://thingsivefoundout.blogspot.com/2012/10/redirecting-after-workflow-task-page.html
However, if you are using 2013 platform, I am afaird there is no way to customize the task form and url. So, I suggest you use 2010 platform.
Best Regards,
Wendy