Head directly to the Alma Hair Page on TSR.
Includes a vast array of vibrant, glossy color swatches supported by color sliders.
If you download third-party retextures like the ones on The Sims Catalog, make sure you also grab the original S-CLUB mesh for it to work properly in your game.
Place the downloaded .package file into your game directory at Documents > Electronic Arts > The Sims 4 > Mods .