How to change link colour?

This is an easy fix – just override the stylesheet in the WP control panel (Appearance > Edit CSS).

Drop this into your stylesheet and see what happens:

a:link {
font-size: 200%;
color: #0B59FF;
}

Editing the theme files directly for any theme is not recommended. Any changes will be lost the next time the theme is upgraded (for example, because of a feature enhancement or a security patch). Since the Hueman theme doesn’t have a custom CSS option, you should either create a child theme or use a CSS plugin (easier).

Good point – child themes are always recommended.

Just to clarify a few things:

Since the Hueman theme doesn’t have a custom CSS option

The version on my site has it. However, theme reviewers did not allow the option in the .org release.

As for the child theme, you can download a sample Hueman child theme from the Help dropdown in theme options.