Why does my sitemap have gray links?
The gray links in your XML sitemap identify the URLs that your browser has recently visited. As this is browser-specific, you may or may not see different gray URLs depending on the browser and computer you are using to view your sitemap.
So, you don’t have to do anything. This is not something for concern!
Note: Google does not see the browser formatting as they retrieve the xml source code.
Are you getting a different error? Check out this article on common XML sitemap errors to see more errors, their causes, and their solutions.