I tried the pagespeed and even though I installed the plugin from Wordpress it appeared:
Leverage browser caching
Setting an expiry date or a maximum age in the HTTP headers for static resources instructs the browser to load newly downloaded resources from local disk rather than over the network. Leverage browser caching for the following cacheable resources:link ... libraries = places & language = en & key & ver = 1.0 (30 minutes)
link (60 minutes)
link (2 hours)
If your links are yours then you can try configuring using .htaccess (if using apache) as I replied at link
If it's a github.io page you can not ( link )
If they are external links, which you have no control over the servers, such as maps.google.com and googleanalitics there is nothing to do
However if they are images you may be able to use a proxy in a programming language, it will depend on the need to use the image, an example with php: link
In short, do your best, some essential service links unfortunately will not give 100/100 or 99/100 in pagespeed, but that's superfluous. Focus on reducing only requests on your server and calling third party APIs only when needed.
For example , I believe you will not use google-maps on every page, so just call this <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> on the required pages.
