Which relation in the data-sheet shows the frequency vs gain relation explicitly?
If I am understanding your question correctly, you have set up a test circuit and as you change the frequency, you are noticing your output distorting (clipping?) and getting worse as the frequency increases, leading to the amplitude decreasing?

Well, this could well be a few issues, but lets look at what could cause issues with an op amp output:

It is driving a load? If so, what is the load it is driving? As shown in the electrical characteristics, the op amp can only output a certain current depending on supply voltage:



Using Ohms Law, you will be able to find out the maximum load it can drive. Now, looking at one of the graphs in the datasheet, you can actually see that the output impedance changes with frequency:



This will again affect the output voltage/waveform depending on the load driven, the frequency, the supply voltage, and the gain.

Of course, there is the supply voltage issue which can cause clipping if the gain is too high, but as you say it seems to be OK up until 10kHz, I think it is safe to assume it isn't that.

There is also the Slew rate. If your op amp is slow, and your gain is high, then your op amp may not be able to actually reach the output voltage in time, hence a decrease in amplitude as the frequency increases. Let's use a classic 741 as an example, whioch has a slew rate of 0.55V/us. This means the output can go from 0-0.5V in 5us. So, to reach 10V on the output, it would take: 10/0.5 = 20us. At, say, 200kHz, a full cycle takes about 6us, showing the output voltage would get nowhere near the 10V output, resorting in a distorted output, and a decrease in amplitude. Of course, that was an extreme example, but you get the picture.

Looking at the datasheet for your amplifier, it does look to be rather slow. I would guess that this is the cause of the output distortion you are seeing. You either need to get a faster op-amp, or decrease the frequency

Next is the one I think is the one you are after (I added in the bits before as they are useful to know and may have something to do with what you are seeing). 

Look at the Gain vs Frequency graph:

 

Using this, we can use a bit of math to see if we are going to get any distortion. I will again need to make some assumptions here as I don't know your input voltage/supply voltage/gain etc.

Let us assume you have an input voltage of 50mV pk-pk and an output voltage of 5V pk-pk, giving us a gain of 100. We can find out what that is in dB (as that is what the graph shows the gain in). To do this, we use: 20Log(100) = 40. This means your gain is 40dB. Looking at the graph, we can see that at this gain value, clipping/amplitude decrease will start to occur near the 2kHz mark:

 

This means that trying to maintain the same gain value above that frequency can't happen. The gain will actually decrease. I believe this is the graph you were interested in, however, there could be other causes, hence the rest of  the information in this answer.