From Gamer Escape's FFXIV Wiki, the free Final Fantasy XIV encyclopedia
When the Chimera's eyes turn Violet, all party members should get into melee range to avoid the AOE attack that will damage everyone outside of melee range. When his eyes are blue, everyone needs to get out of melee range to avoid this attack.
Chimera will also focus his gaze on a target. When he does, a blue ball of energy will chase a targeted player. The player needs to move away from this ball once it stops moving, when it will cast an AOE paralysis.
Near the end of the battle, he will also cast Frostbite, which will cast random circles of ice on the ground. Players need to avoid standing in these.
Tanks should face Chimera away from the party as he has several cone-based attacks which need to be avoided by all party members.