How does a native English speaker pronounce ...

[Fmr President & Senator Polnut]

Kuh-lor-ado

[Okay, maybe Mike Johnson is a competent parliamentarian.]

Kah-loe-rah-doe... but I usually say the "loe" as a "luh" and the "doe" as a "dah"

That's how most Southerners I've known have said it. I say it Kaw-luh-rah-dough, or sometimes something like Cole-uh-rah-dough.

[ilikeverin]

I used to pronounce it with [æ], but I've switched to [ɑ] because I've learned that's what native Coloradans prefer.

https://www.google.com/webhp?sourceid=chrome-instant&ie=UTF-8#hl=en&output=search&sclient=psy-ab&q=define%20colorado&oq=&gs_l=&pbx=1&fp=cda1f62fcb8b192d&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&biw=1680&bih=807

click the speaker icon and it will say the word.

That's not how I say that.  The speaker really elevates the "ah" sound...or maybe he just places way more emphasis on it.  I saw much more...fluently?  Rollingly?  Not sure how to describe the difference.

Well, that's would be the Spanish way to say it, the tonical accent being on next-to-last sound when not specified. That would be the original way of saying it and the textbook way, but it may have mutated since then with use by Americans.

Of course the pronunciation there isn't the way they would pronounce it in Spanish; the [æ] sound doesn't exist in Spanish!  (nor [ə], for that matter)