How to express the idea that a person feels "anxious" because someone said something that is somehow relating / touching to his/her bad intention?

In Vietnamese, "the face turns pale or green or blue" means "anxiety"?

I remember, in English, "red" means "(of the face) bright red or pink, especially because you are angry, embarrassed or ashamed", Example "She went red as a beet." Source

Ok, now here is a situation. There was a young girl who met an old guy on the online dating site. The young girl did not love him but just wanted to use him for money. When on the first date, the old man said to her "I met many girls only and 95% of them just wanted to use me for money". After listened to that, the girl felt anxious because someone said something that is somehow relating / touching to her bad intention. Note: the old man may not know she is a cheater at the first meeting.

2nd example, there was a bad young man who wanted to steal money from his grandmom. While having a conversation, the old lady said to her grandson "There are many people want to steal my money". After listened to that, the young man felt anxious because someone said something that is somehow relating / touching to his bad intention. The old lady may not know her grandson is a cheater at the conversation.

3rd example, a lazy student wanted to bring illegal print-out with him to the exam. At the examination room, the exam supervisor had a chat with him. The supervisor said that there are some students were caught last year because the brought illegal print-out with them to the exam. After listened to that, the bad student felt anxious because someone said something that is somehow relating / touching to his bad intention.

In 3 above examples, the Vietnamese can say "the face turns pale / green / blue" to express the idea that a person feels anxious because someone said something that is somehow relating / touching to his/her bad intention.

So,

How to express the idea that a person feels "anxious" because someone said something that is somehow relating / touching to his/her bad intention?

We got "go red" but what about "go pale / green / blue"?

If you are looking for someone's face to passively express that anxiety by changing color, "he/she blanched" or "he/she turned ashen" are used to show that the subject feels fear - which could be fear of being discovered or fear of bodily harm. Of course, as you suggested, turning pale or turning white would be another way to express that reaction of the subject's face draining of blood due to an extreme emotion such as fear or as michael_timofeev offered, guilt.

Green is used to show someone who is feeling queasy or about to be sick (vomit) which can also be caused by fear.

Blue is almost always used to describe someone who is oxygen-deprived.

Red typically shows anger, shame, embarrassment and also someone who is overheated.

Purple is used to show extreme rage. If someone is described as purple with rage, it's also common to note that their eyes are bulging, too. (That last bit was not really relevant to the question but it popped in my mind as I was typing this!)

"Blanch" - relevant definition from the Oxford Dictionaries:

2 [no object] (Of a person) grow pale from shock, fear, or a similar emotion: ‘many people blanch at the suggestion’

‘their faces blanched with fear’

"Ashen" - also from the Oxford Dictionaries:

1.1 (Of a person’s face) very pale with shock, fear, or illness.