Yes you can edit this. If you take a look at the StudioPress Code Snippets page you’ll see this – http://my.studiopress.com/snippets/post-excerpts/#content-more-link ….you can add that code, but I would suggest renaming the function since it is already present in your portfolio file (to avoid duplicate errors). If you’re not using the portfolio template, then you can just add the code as is –
Then you can style it however you want by adding .more-link in your css.