MATLAB doesn't have really great 3D volume visualization. About the best it can do are surface renderings or cutaway views, like you can see in the visualizations chapter in the help (MATLAB->Graphics->2-D and 3-D Plots->Surfaces, Volumes, and Polygons), for example the slice() or isosurface() functions. Perhaps one of those will work for you. If you want a two and a half D rendering, you can take one of your planes and pass it into surf(). Or you can somehow compress your image into a 2D image, like sum it along one of the dimensions or take a "maximum intensity projection" or something like that, then display it with image() or imshow(), after which you can apply a colormap if you want.
If the points you'd really like to visualize are scattered around various locations in your volume, like a wavy sheet, a surface like an ellipsoid, or even just isolated points, then you might be able to use plot3() or scatter3(). It's hard to make recommendation for a 3D array in general until we know what in that would you like to display.
