Go to a local auto paint store and tell them the year, make, model, and
color.  Have them mix up a small batch of paint, take it home and spray
it on a primered test board.  Hold the board up to the car under the
appropriate lighting.  If you don't like the match, take it back to the
store and have them mix up a new one (lighter, darker, more blue,
yellow, red, whatever).  Repeat until you are satisified with the
results.

You'll want to sand down the damaged areas before painting.  Ask the
auto paint store what they would recommend for a primer coat.  And when
you are done, don't forget the clearcoat.

Or you could just drive to a local "Cosmetics" touch up shop - or even
your local Lexus dealer - and have them do this for you.