It is possible to change the color of the axes as well as the data points in a plot. The plot could have been generated using any of the functions used for creating graphs, such as, "plot", "plotyy", etc. As long as the axes handle is available, we can alter the properties of the plot programmatically. Consider the following code snippet that shows how "plotyy" can be used to plot multiple signals and how the color of the two axes can be altered:
As an alternative, the properties of the figure can also be modified interactively from the figure window. In the "Figure" window, click on "View" and select "Plot Browser". The properties of the axes can be modified by double-clicking the corresponding axis. This opens the "Property Editor" window.
I hope this answers your query.