It should be a Dahlia variabilis. I'm not fully sure, since, as his name suggests, it may show very different types of flowers and colors, depending on the variety. Try to search this name on google.
Anyway, the shot is very nice, thought I have not specific suggestions on how to PP it. Perhaps you could try to blur a bit the background to focus more the attention on the flower.
I see from the EXIF: Canon PowerShot S45 at 7.1mm, 1/400s, f/2.8, iso unusually not shown.
Maybe the S45 has drawbacks I'm not aware of, but I would actually choose my Canon S100 in preference to my DSLR for a flower shot because of the greater DoF allowing the whole bloom to be in focus.I feel this is a pretty good capture considering the equipment I had, should I PP this in any way?
The downside is, as Giacomo suggests, that sometimes the background is also a bit too well defined.
Looking at the background on this shot, I wonder if you could have moved a little further round to your right, to exclude some of the bright sky and colourful blooms behind on the right.
However, you have this capture (and it is quite good), so in PP (post processing), you might try a slight crop, some additional blurring and toning down of the distractions in the background and perhaps a vignette.
Hope that helps,
Yes looks like one of the 'Cactus type' Dahlia flowers to me.
The background is rather cluttered but in this case I don't find that to be a problem.
Maybe a very slight crop from the bottom and left side would be worth trying.
Focus and exposure are good.