Google has finally started to roll out the Google Play Store with Material Design similar to the Android L to all the devices out there. But, the roll out can take hours or even days to arrive for your Android devices.
Android L includes a new Material Design which is a flat user interface unlike previous Android versions. Although Android L is not available for all devices out there where it is only available on selective devices like the Nexus 5 and Nexus 4. But, Google has started to roll out updates for its apps to make their interface similar to Material Design from Android L.
Google Play Store is the most recent Google app to be updated with Material Design and you can download the apk right now to get the all-new material design on your Android device.
The apk has the version 5.0.31 and can be downloaded right now from the link below. For those of you wondering how to install apk files on your Android device can see this tutorial.