Hi Narayan, hope you would not mind if I say something!
Hi Pradish,
If Narayan got you to what you wanted, then please ignore.
I have a feeling that what you want is, to highlight all cells in a spreadsheet which has got formula (any cell that is linked to other cells, will have formula in order to be able to be linked to other cells).
On your spreadsheet, hit Ctrl+G, Click on "Special", click on "Formulas" and click on "OK", button. All the cells on your sheet that have got formula, will be selected. Please do not click anywhere on the sheet, first apply a background color of your choice. All the cells selected in previous step, will be highlighted with the background color you applied.
Hope this helps!