Access support for dyslexia sufferers

I have never had to think seriously about dyslexic users until undertaking a site design for an organisaton providing support. On researching the needs of people with reading difficulties I found that they could often be helped by choosing the font, size, color and background colour. Here is a site that provides such assistance http://www.dyslexiaaction.org.uk/

If have found reference to WPChameleon plugin which seems no longer to exist and in other threads esmi has suggested setting up a series of alternative themes and usinh a Theme Changer plugin. Well, there is no such current plugin that offers a selector widget for site visitors – the ones that are up to date seem to be for presenting device- or browser-specific site versions automatically, or to help site developers.

It is suggested that one in ten people suffers from reading difficulties. Can anyone please suggest how I can present an elegant help solution in WordPress?