Bhuwaneshwar, does it have to be Label widget? Why I am asking this is because Label Widget is pretty simple widget and doesn't have something like State-based Formatting which is available with Value display widget.
If it has to be Label widget for displaying data then may be you can workaround using multiple of those Label widgets with predefined color style, placed on top of each other and set disable and enable the visibility of the label of the required color based on the output you are getting from the service.
Hope that helps.
