You might look at the SUBGROUP option. This might mean that you have to "pre-summarize" your data, so that you can creating a subgrouping variable based on your condition. (instead of graphing the unsummarized data, then, you would graph the summarized data). You could use DATA step logic or a user-defined format to set a value for the subgrouping variable. But, no matter how you set the subgrouping variable -- let's call this subgrouping variable, Category.
Then, your VBAR3D statement would look something like this:
vbar3d graph_var / sumvar=numvar
Without any specific instructions, SAS/Graph will cycle through the current color list. You can explicitly set PATTERN statements to control the colors of the subgrouped bars. If you had 4 categories, then you would use 4 PATTERN statements, if you only had 2 categories, then you would use 2 PATTERN statements.