I used simple XML sitemap module to create a sitemap for search engines but now I need one sitemap for visitors. Can I create this manually instead of using a module because the site already has too many modules? I was thinking to create a basic page and just add the links there one by one. Is this a good way?
Depends on how often your site changes and who makes the changes.
If it's a single person and that person can remember to add new pages to the site map then manual is probably OK.
If you have non-technical people adding pages to the site, chances are that they will not update the map just add it to the menu.
With a module, the sitemap can be automatically updated as the things change.
Remember changes can also include things like page or menu titles that feed into the site map.
There is a module that does what you want, and it isn't XML Sitemap but just Sitemap:
This module provides a site map that gives visitors an overview of your site. It can also display the RSS feeds for all blogs and categories.
Drupal generates the RSS feeds automatically but few seems to be aware that they exist.
The site map can display the following items:
- A message to be displayed above the site map.
- Any books.
- Any menus that will be displayed fully expanded.
- Any vocabularies, with all the terms expanded. Optionally with term depth, node counts, and RSS feeds.
- A syndication block, the "more" link goes to the site map.
because the site already has too many modules?
There is really no way to quantify this for you. There isn't necessarily a module limit, your limit is defined by the limits of your hosting space. The performance impact of adding the Sitemap module, vs spending hours doing it yourself (to reach the same point but with 10x the maintenance) is negligible, especially since you can cache it in Drupal and use things like Varnish or Memcache if your host supports it (if not, find an updated host!). You will be fine.
Easiest way perhaps using the Main menu block and displaying them at the sitemap page's content region.
If you already have the Menu Block installed, it'll give you more flexibility configuring how deep to expand the shown menus as well.
Then you can simply style the menu block with CSS.