The diagram below shows all the notes on the fretboard of a guitar tuned to standard tuning. (E A D G B E)
If you are trying to memorize this diagram it is best to start by learning the notes on the low E and A strings. Once you have these two string memorized you can use a bunch of different techniques to figure out where the rest of the notes on your fretboard are. In time you should be able to memorize the whole thng with just a little effort.
One of the first things I cover with brand new guitar players is the name of the notes on the open strings of the guitar. If you have trouble learning these names just remember the phrase: "Even Al Did Good Before Eatting" This is a good memory tool to remember the string names: "E" "A" "D" "G" "B" "E"