If you are not happy with the hyperlink color that appears on your blog, you can change it. A simple way to do this is to change the color of the text of the hyperlink before you hit the Insert/edit link button.
Here are some examples that provide links to the WordPress forum post where I found this helpful tip.
You can even bold and/or italicize the hyperlink text as well as add color to it before creating a link:
Now you can experiment and find out which combination of font style (regular, bold, italic) and font color will work best for your blog.