Hi Himanshu,
The BackColor of a cell is normally controlled through the style.BackColor property of the cell. This should work for any cell unless you are handling some event that prevents this default behavior. This should n't work for theme enabled header (RowHeader ,ColumnHeader) cells and PushButtons. You need to subscribe to the grid's TableControlDrawCell event for drawing the cells. There you can use e.Inner.Graphics.FillRectanlge to draw the backcolor and then set e.Inner.Cancel = true to indicate you have handled the drawing.
Here is a sample that shows how you can use this event to draw backcolor in cells.
ThemeTable_51a1976b.zipOne comment though is that the backcolor of buttons is not control through the style object for the cell. Instead, you will have to handle an event to color buttons.
Here is a forum thread discussing coloring buttons.
http://www.syncfusion.com/Support/Forums/message.aspx?MessageID=26772 Let me know if this helps.
Best Regards,
Haneef