Sorry, but I have lost my manuscript for the cadenza. I performed this about 10 years ago, I did not have access to a notator program.
Basically, I started with the alberti bass theme, played some scales, then chromatic scales to modulate, some alternate broken chords, arpeggios and that was about it. The cadenza doesn't have to be long. It's all up to you - a couple of measures should be fine. I know you probably get a little intimidated from all the cd recordings, and you feel that a cadenza has to be virtuosic and complement the entire concerto.
Give it a try. 300 years ago, all the performers were making up their own cadenzas. Actually they would improvise this.