But assuming you have all your LEDs in parallel, each with a series current limiting resistor, and assuming each is pulling only 40 mA...question, is this a measured or calculated current draw? Because if your circuit is only a 320 mA load, the 7805 should be more than adequate.
Are there other circuits also involved that you didn't mention?
If not, then this is a troubleshooting issue, not a design issue. You need to verify the polarity of your LEDs. Also, what is the input voltage source? Batteries? Or a rectifier and transformer? Is the rectifier properly rated?
If this is a battery voltage source, is it new? Have you tried replacing it? I'm thinking likely your battery is going dead.
If none of this is the case, then verify the bias of all your diodes and make sure none of them are faulty. You might remove each diode one by one to see if one is shorted. Even a shorted resistor isn't an unreasonable failure. Do a physical check, touch each resistor and diode to see if one is getting too hot.
Use a multimeter. Take a measurement of all your voltage drops and find one that is behaving differently.