set an example for还是to

都可以，for后面加名、代词，to后面加动词。例如：
set an example for your point, please.(请举例证明你的观点)
set an axample to illustrate your point, please.(同上)

Her diligence has set an example to the others.

我去英美等过网站上搜索了下，两种用法都有！！
It was possible to resist, and those people set an example for others.
反抗不是行不通，这些人为他人竖立了榜样。
She arrived at the office early to set an example to the others.
她很早就来到办公室,作为他人的表率。

set an example to sb.为某人树立榜样。
我们书上刚学的。

set an example for
以.为例

set an example to
做...榜样, 树立(好)榜样
我查词典得到的答案!