Answer:
I could make 280 different color patterns. 
Step-by-step explanation:
Let's suppose that we want to arrange in a straight line N objects. 
Let's also suppose that in this N objects there are N1 objects of a certain class (this N1 objects are equal between them), N2 objects of a certain class (this N2 objects are also equal between them), ... , Nn objects of a certain class.
Mathematically :

This is a condition to apply the following equation
The total ways to arrange them are : 

Where ''!'' is the factorial number. 
For example : 
4! = 4 x 3 x 2 x 1
3! = 3 x 2 x 1
1! = 1
0! is defined as 1 
In this exercise we only need to apply this equation to answer the question. 
There are 8 blocks.
4 are white
3 are yellow 
1 is purple 

The first condition is satisfied. Now, we can apply the equation to find the arrangements. 

There are 280 different color patterns.