You can use the text touchup tool to first change the color of text for all text you want to make links. Then make the the link properties, via the link properties bar, no color.
If you make one link and then right click on it to get the pop up menu/properties, you can set properties to invisible rectangle or visible rectangle and then UNDERLINE from Line Style drop down if you want the links to look just like common text web links. Just pick the same line color as the text color you selcted in text touchup.
You can also use the botton tool for links, which gives you many more options including text color, but it's a bit cumbersome and time consuming if you have many links.
It does seem odd that Acrobat doesn't giv ethe option for just coloring the text in links like common web design apps do - at least in my version 6.
Using OSX 10.3.9 on a G4