For each layer, you can specify the color used for selection in the layer properties. Right-click on the layer title in the Table of Contents (e.g., MOUSE Links), click Properties in the context menu. On the Selection tab, change the option to "with this symbol" and choose the color/symbol you'd prefer.
Within ESRI ArcMap, there's an overall selection color specified in Selection > Selection Options, but there isn't an equivalent in Mike Urban. If you're into programming, I'm guessing there's a way to specify the selection color via ArcObjects, which probably wouldn't be too hard to write as a Mike Urban extension.
Thanks,
Brian