tags (see above the text box when posting), we can see your indentation (which is important in Python, btw).
## Add color map to DRGs
##====================================
import arcpy
from arcpy import env
# Set workspace
arcpy.env.workspace = "Y:\base_data\State\IL\100k_DRGs"
# Get list of grids
rasterList = arcpy.ListRasters("*", "GRID")
for raster in rasterList:
## Add Colormap
try:
##Assign colormap using clr file
arcpy.AddColormap_management(raster, "#", "ISA_DRG.clr")
print raster
except:
print "Add Colormap example failed."
print arcpy.GetMessages()