The logs go to the regular .NET system diagnostics. To see them you can add a trace listener to your web.config, and you'll see the traces going to the file you specify. For an example, see the snippet below.
<system.diagnostics>
<trace autoflush="true">
<listeners>
<add name="default"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="c:\temp\trace.log" />
</listeners>
</trace>
</system.diagnostics>