The automaton that accepts the regular expression of any number of "a" can be represented by the following diagram:

```
a
-------------->
| |
| v
| q0 q1
| /|\ |
| | |
| |a |a
| | |
| v |
| q2 q3
| |\ |
| | |
| |a |a
| | |
| v |
| q4 q5
| |\ |
| | |
| |a |a
| | |
| v |
------q6<------>

```

In this automaton, there are seven states q0, q1, q2, q3, q4, q5, and q6. The initial state is q0 and the accepting state is q6. The transition function is defined as follows:

δ(q0, a) = q1
δ(q1, a) = q2
δ(q2, a) = q3
δ(q3, a) = q4
δ(q4, a) = q5
δ(q5, a) = q6

The automaton starts in the initial state q0. If the input is the symbol "a", it transitions to state q1. From q1, if the input is "a", it transitions to state q2, and so on until it reaches state q6. At this point, the automaton accepts the input and halts.

If the input is not a symbol "a", the automaton transitions to a dead state that does not accept any input.

This automaton accepts any string of "a"s of any length, including the empty string.