GraphView offers many options to style your charts individually. The styles are so ordered that they are to the specific modules like the Series, the Legend, the Grid and some general styles. So if you are looking for styling options you have to take a look into these objects.
Hint: New styles are coming by time and not all features are listed here. Please take a look at the API reference documentation, to see all options.
These are options that are general that thus on the GraphView object.
The styles regarding the labels and the grid belong to the GridLabelRenderer, which you can access via graphView.getGridLabelRenderer();
There are many options:
Viewport options are about the what you actually see in the area where the data gets plotted.
You can set the options to the graphView.getViewport() object.
Some options are related to the series, so you set them at the Series object. The most options are related to the type of the series and so you have to take a deeper look at the specific types here.
This are the general options regardless of the type: