Here is some general guidance on how to structure your portfolio. These should roughly cover all types of game design portfolios.
Pick 1-3 projects you are really proud of and make them really prominent in your portfolio. Include an image of the game, the name of the game, the name of the studio and your role.
Write down a short but sweet list of what skills you bring to projects. An employer should be able to skip through these and get an idea of what your particular strengths are. Make it really easy for them to compare you to their list of job specs! For example:
Your contact details should be easily accessible ideally from all pages.
When clicking on a project, an employer should be able to read more information about it and what your role in the project was. An ideal project description could be structured like this: