Hi Vamsi,
I was able to locate Windows 8 compatible AMD Radeon HD 6470M graphics drivers for a different system model. We can try installing on your system which might work. Refer the following link to download and save the drivers: http://dell.to/1csS02d
Refer the following link for instructions to uninstall the existing graphics drivers: http://dell.to/11rKazZ
Once the drivers are uninstalled, restart the computer and run the previous downloaded file. Follow the on-screen instructions to install the drivers.
Do let me know the results.