If I was doing a sliver deck, I'd probably do 4 colors too. With enough dual lands and gemhide slivers, you can do just fine with 4 colors. I'd mostly go Naya, with a splash of blue for Wing Sliver and Shadow Sliver. Shifting Sliver and Crystalline Sliver for the side as well. Slivers are fun.
WTT 16" Stiffi Switch Tip for a 12" or 14" Tip