NodeXL assigns a color and shape to each group that you create using one of the techniques discussed in Creating Groups. When you show the graph, all the vertices in the group will have that color and shape—group A's vertices might be blue disks, for example, and group B's vertices might be orange spheres. These group colors and shapes override any individual values you might have entered in the Color and Shape columns on the Vertices worksheet. In other words, those columns get ignored. (You can, however, tell NodeXL to not ignore those columns. See Changing How Vertex Colors and Shapes are Specified.)
Most people use the color and shape combinations that NodeXL assigns to the groups, but you can edit the colors and shapes if you are unhappy with them. Note, however, that if you create groups, edit the group colors and shapes, and then create groups again, your edited colors and shapes will get overwritten and you will have to edit them again. Therefore you should create all your groups first, then edit the group colors and shapes.
In addition to using vertex colors and shapes to distinguish groups from one another, NodeXL can lay out each group within its own box in the Graph Pane.
NodeXL arranges the group boxes in what is called a squarified treemap. The size of each box is proportional to the number of vertices in the box's group.
If you choose to combine intergroup edges, all edges between a pair of groups are combined into a single edge whose width reflects the number of combined edges. This is useful for reducing graph clutter.
If you combine intergroup edges and the Edges worksheet has an Edge Weight column, the edge weights are used to determine the width of a combined edge. Edge Weight column values should be greater than zero. If a value is zero or less, it is ignored and 1.0 is used instead.
You can tell NodeXL to temporarily skip all the groups you've created without actually removing the groups from the workbook.
When you tell NodeXL to skip all the groups, it completely ignores everything on the Groups and Group Vertices worksheets when the graph is shown. It also starts paying attention to the Color and Shape columns on the Vertices worksheet again, so the graph's vertices take on any colors and shapes you previously assigned to them.
You can also skip individual groups. See Hiding and Skipping Groups.
As explained above, NodeXL assigns a color and shape to each group that you create. The colors and shapes are stored in the Groups worksheet, and the colors and shapes specified in the Vertices worksheet are ignored.
Advanced users may want to use the colors or shapes from the Vertices worksheet instead. For example, you may want to combine the group colors that NodeXL assigns with the individual vertex shapes that you specified on the Vertices worksheet. This can be particularly useful when the individual vertices have a Shape of Image or Label.