Change the text colors in Tags Cloud

Open file engine.css in your current template

Find:

clouds_xsmall {
    font-size: x-small;
}
.clouds_small {
    font-size: small;
}
.clouds_medium {
    font-size: medium;
}
.clouds_large {
    font-size: large;
}
.clouds_xlarge {
    font-size: x-large;
}

Replace with:

.clouds_xsmall {
color: red;
    font-size: x-small;
}
.clouds_small {
color: green;
    font-size: small;
}
.clouds_medium {
color: blue;
    font-size: medium;
}
.clouds_large {    color: #4b719e;
    font-size: large;
}
.clouds_xlarge {    color: black;
    font-size: x-large;
}

You can change the colors as you wishes :)