SRTM data (Shuttle Radar Topographic Mission), sometimes do not immediately appear attractive when displayed in ArcGIS. SRTM display all gray look, there is no difference between one place to another as shown below.
The cause of the appearance of the SRTM data as shown above is not arranged symbology. Try performing the following steps
A. Open the properties of the layer srtm_58_14.ASC (adjust the file name that you are open). Accessing the properties of the layer can be done by double-click on the layer or right-click> Properties
2. Click on the symbology tab as shown below