For what it is worth, there is also colorDefault constant that is automatically adjusted depending on background so it is visible. It is dark on light backgrounds and light on dark backgrounds. It is connected with chart themes.
It is recommended to use colorDefault if you want Plot to work with any chart theme.
@thankyou18 I think "eye-friendly" is all in the eye of the beholder. But some ideas for you, take a look at the many options.
AmiBroker color palette, Tools-->Preferences-->Color
Other useful functions and links,
ColorRGB( red, green, blue )
ColorHSB( hue, saturation, brightness )