Invert the image.
Image > Adjust > Invert
Shortcut : Ctrl + I
Apply Filter > Distort > Polar Coordinates with the option Rectangular to Polar.
Go to Image > Adjust > Hue/Saturation
Shortcut: Ctrl + U
Click the colorize check box.
I used the values
Hue: 360, Sat. 80 and Ligthness 0.
Basic Ray effect is appeared so far. Let's make it look cooler.
Duplicate the layer.Layer > Duplicate Layer
Set the top layer blending option to Screen.
Select the bottom layer and apply gaussian blur.
Filter > Blur > Gaussian Blur
I set the value , 7.0
Duplicate the top layer and select the top layer. Decrease the size of the layer around %50 and turn it 90 CW.
Edit > Free Transform
Shortcut: Ctrl + T
Hold Shift + Alt to constrain proportions of the layer.
Apply Image > Adjust > Hue/Saturation
Click the
colorize check box. And choose a
color of your preference.
More Tutorials: 
