How can I cause a color change using an event?

local tweenService = game:GetService("TweenService")
local seat = workspace.Seat

local faces = { --table of face id's. Keep in mind that you have to get these faces from the Toolbox. Faces from the catalog will not work.
	5303681402,
	5646474823,
	275614649
}

seat:GetPropertyChangedSignal("Occupant"):Connect(function() --detects when occupant changes
	local humanoid = seat.Occupant 
	if humanoid then --if player is in the seat then
		local character = humanoid.Parent
		local randomColor = Color3.fromRGB(math.random(0,255),math.random(0,255),math.random(0,255)) --generate a random color
		local tweenInfo = TweenInfo.new( --construct tween info
			5, -- Time
			Enum.EasingStyle.Linear, -- EasingStyle
			Enum.EasingDirection.Out, -- EasingDirection
			0, -- RepeatCount (when less than zero the tween will loop indefinitely)
			false, -- Reverses (tween will reverse once reaching it's goal)
			0 -- DelayTime
		)
		for _,part in pairs(character:GetChildren()) do --go through all the children of the player's character
			if part:IsA("BasePart") then --if the child is a part then
				local tween = tweenService:Create( --construct a tween to change colors
					part,
					tweenInfo,
					{
						Color = randomColor
					}
				)
				tween:Play() --play the tween
			end
			if part.Name == "Head" then 
				local face = part.face --get the player's face in the player's head
				local newface = Instance.new("Decal",part) 
				newface.Name = "face"
				newface.Transparency = 1
				newface.Texture = "rbxassetid://"..faces[math.random(1,#faces)] --generate a random face
				local tween1 = tweenService:Create( --construct a tween to make the old face slowly disappear
					face,
					tweenInfo,
					{
						Transparency = 1
					}
				)
				local tween2 = tweenService:Create( --construct to make the new face slowly appear
					newface,
					tweenInfo,
					{
						Transparency = 0
					}
				)
				tween1:Play()
				tween2:Play()
				tween1.Completed:Wait() --wait until the tween that makes the old face disappear to destroy the old face
				face:Destroy()
			end
		end
	end
end)