Hello Vandana Matai,
the origin of the entire GUI application is the upper left corner (0,0). Thus, the origin of the graph is also in the upper left corner and the X axis is going right and the Y axis is going down.
In order to adapt your graph you have several possibilities - depending on your implementation:
You can adapt your Y values so that they are following the default orientation, or if your graph is based on Component Template 'Graph' you can change the property ScaleY from 1.0 to -1.0 to get all values mirrored on the X-axis.
If you are using your own implementation based on StrokedPath you can use the property FlipY to achieve the same effect.
I hope this helps.
Best regards,
Manfred.