It depends on what you mean by graphics.
If it is a photo, name the photo with a keyword, use the alt text to include the keyword as well. Include a good meta description and text to describe it. Many people don't automatically load images.
If you are talking about flash or other video type material, there are things you can do to improve the
SEO of the page.
Include a transcript on the page to get text available. Describe the video in the same way Youtube does to the search engines.
The search engines don't see things the way we see things. They can interpret text to give you relevant results. Without text they don't have a way to rate and evaluate your material.
So if you provide graphics always provide a text equivalent to make sure the search engines can understand it.