Add this at the end of .htaccess file

## EXPIRES CACHING ##
<IfModule mod_expires.c>
ExpiresActive On
ExpiresByType image/jpg "access 1 week"
ExpiresByType image/jpeg "access 1 week"
ExpiresByType image/gif "access 1 week"
ExpiresByType image/png "access 1 week"
ExpiresByType text/css "access 1 week"
ExpiresByType application/pdf "access 1 week"
ExpiresByType application/javascript "access 1 week"
ExpiresByType application/x-javascript "access 1 week"
ExpiresByType application/x-shockwave-flash "access 1 week"
ExpiresByType image/x-icon "access 1 week"
ExpiresDefault "access 1 week"
</IfModule>
<IfModule mod_headers.c>
 <FilesMatch ".(js|css|xml|gz|html)$">
   Header append Vary: Accept-Encoding
 </FilesMatch>
Header set Connection keep-alive
</IfModule>
## EXPIRES CACHING ##